Category: Water Softener

When you compare water softener cost, the purchase price is only one part of the calculation. Hard water may already be costing your household money through limescale, less efficient hot-water equipment, frequent descaling, higher cleaning-product use and added pressure on appliances and fittings.

A water softener removes the calcium and magnesium that cause hardness before the water travels around your home. The Drinking Water Inspectorate explains how ion-exchange softeners replace these hardness minerals with sodium, helping prevent new limescale where softened water is supplied. The potential savings therefore come from several smaller household costs rather than one guaranteed reduction on a single bill.

How much you could save depends on your water hardness, household size, hot-water use, cleaning habits, appliances and chosen system. Start by checking the water hardness in your area, then compare the full water softener system cost with what you currently spend managing hard water.

Lower energy waste from limescale

Limescale is easy to spot around a tap or inside a kettle, but some of the most expensive build-up is hidden. The same chalky deposits can form on heating elements, inside hot-water systems and along narrow water pathways. Scale creates an insulating layer between the heat source and the water, so the system may have to work harder to deliver the same result.

The effect is not identical in every boiler, cylinder or water heater, and a softener should never be presented as an instant fix for an inefficient heating system. However, reducing the minerals that cause new scale helps protect heat-transfer surfaces from further build-up. Over time, that can help the equipment operate closer to its intended condition instead of fighting an increasingly thick layer of limescale.

Softened water may also help existing scale reduce gradually, although the rate varies by household and plumbing system. Your potential energy saving will depend on how hard your water is, how much hot water you use, the type and condition of your equipment and your energy tariff. The most realistic benefit is protection against avoidable energy waste, not a guaranteed percentage reduction for every home.

In practice, that benefit may show up as preventing costs from creeping higher rather than producing an immediate dramatic fall in your bill. A recently serviced system with little existing scale may have less efficiency to recover, while an older installation in a very hard-water area may have faced years of mineral build-up.

Help protect appliances from hard-water build-up

A typical home sends hard water through more than the boiler. Washing machines, dishwashers, kettles, coffee machines, shower fittings and taps are all exposed to the same calcium and magnesium. As water heats or evaporates, those minerals remain behind and form scale on surfaces and internal components.

A whole-home soft water system tackles the problem before the water reaches these appliances. By limiting new limescale, it can help keep heating elements, spray arms, valves and narrow waterways cleaner. That may mean less descaling and fewer hard-water-related maintenance problems over time.

The saving here is often an avoided cost rather than a monthly credit you can see on a statement. A kettle that needs descaling less often, a showerhead that keeps its flow and a dishwasher with less scale on internal parts can require less attention. Across several appliances, those small reductions in maintenance can add up over years of ownership.

A water softener cannot prevent every fault or guarantee that an appliance will never need repair. Age, usage, installation quality and mechanical wear still matter. Its financial value comes from reducing one persistent source of strain. The wider benefits of a water softener include protection against limescale throughout the home, not just cleaner-looking taps and shower screens.

Use less detergent, soap and cleaning product

Hard water does not stop soap or detergent from working, but it makes them less efficient. Hardness minerals react with soaps and can leave residue behind, while shampoos, washing-up liquid and laundry products may produce less lather. The natural response is often to add another squeeze, scoop or capful.

Softened water lets these products lather and rinse more readily, so many households find they can reduce the amount they use. Controlled Water Quality Research Foundation laundry and dishwasher testing found that lower detergent doses could achieve comparable or better cleaning in softened water under the study conditions. Household results will vary, but the research supports the practical advice to reduce product gradually rather than continuing to dose for hard water.

The savings become more meaningful when repeated across laundry detergent, dishwasher detergent, hand soap, body wash, shampoo and household cleaners. Using the correct smaller amount can also help products rinse away more cleanly, rather than simply producing excessive foam.

Spend less on limescale removers and descalers

Hard-water households often keep several products specifically for scale: kettle descaler, shower-spray cleaner, toilet limescale remover and stronger solutions for taps or showerheads. These products address the deposits after they appear, so the expense returns as the scale returns.

A water softener takes a different approach by removing the hardness minerals at source. When softened water reaches your bathroom, kitchen and appliances, new limescale is far less likely to form. You may still buy ordinary cleaning products for hygiene and everyday dirt, but you can reduce your reliance on specialist acids, descalers and repeated heavy scrubbing.

This is also a time saving, even if it is harder to place an exact pound value on it. Fewer chalky marks on shower glass, taps and sinks can mean shorter cleaning sessions and less frequent deep descaling. For many households, that reduction in routine effort is part of the return on a softener alongside the products no longer going into the shopping basket.

Understand the running costs too

A fair soft water system price comparison should include more than the equipment itself. Ask for the purchase price, installation cost, salt use, water used during regeneration, warranty cover, service options and any finance or care-plan payments. A low upfront figure can be misleading if the system is poorly matched to the home or expensive to operate.

The HarveyArc water softener uses a non-electric core softening mechanism, so it does not require mains electricity to soften the water. The HarveyArc uses 300 g of salt and 17 litres of water per regeneration. It uses compact Mini Curve Salt Blocks, which are designed for convenient loading and are available through Culligan Harvey’s water softener salt range.

Non-electric does not mean cost-free: salt and regeneration water remain ongoing inputs. The useful comparison is whether the system regenerates according to actual demand and whether the supplier publishes enough information to estimate those inputs. You should also consider how the chosen payment option affects your monthly budget and the total amount paid over time.

Why Harvey’s design matters for savings

Harvey water softeners use a twin-cylinder design. One cylinder can regenerate while the other continues softening, providing continuous softened water rather than leaving a regular period when the home is unprotected from hardness. That consistency matters because the potential savings depend on keeping limescale-causing minerals away from the hot-water system, appliances and cleaning routine throughout the day.

The softening mechanism is powered by water pressure rather than mains electricity. Accurate metering records water use and combines it with the hardness setting to determine when regeneration is needed. This demand-based approach is designed to avoid regenerating on a simple fixed timetable when the resin still has capacity available.

HarveyArc is also compact enough to fit under many kitchen sinks, subject to the cupboard, pipework and installation layout. Its design does not make every household saving identical, but it brings together features that influence long-term value: continuous soft water, no mains electricity for core operation, demand-based regeneration and published operating specifications.

So, how much money could you save?

There is no honest universal figure. A larger family in a very hard-water area may have more opportunities to save than a smaller household with moderate hardness and low hot-water use. Your result also depends on the age of your appliances, how much detergent and descaler you currently buy and the water softener system cost.

To build a realistic household estimate, review what you currently spend in the following areas:

• Hot-water energy: Consider how much hot water your household uses and whether limescale is already affecting the system.
• Appliance care: Include descaling, engineer visits and hard-water-related maintenance, but do not assume every future repair will disappear.
• Detergent and toiletries: Track laundry detergent, dishwasher products, soap, shampoo and body wash, then reduce dosing carefully after softening.
• Cleaning and descaling products: Add up specialist limescale removers and the frequency with which you replace them.
• Softener ownership: Include installation, salt, regeneration water, servicing and the total cost of any payment agreement.

A personalised assessment is more useful than an online average. A free Culligan Harvey water softener demonstration can include a hardness test, plumbing survey, savings calculation and full quotation. You can also request a personalised quote to compare the price of Harvey water softeners with the hard-water costs specific to your home.

Key takeaways

• Water softener cost is only the starting point: Compare purchase and installation with salt, regeneration water, servicing and payment-plan costs.
• Savings come from several areas: Softened water may reduce limescale-related energy waste, product use and appliance maintenance.
• Exact savings vary: Water hardness, household size, hot-water use, appliances and shopping habits all affect the result.
• System efficiency matters: Harvey combines twin-cylinder softening, non-electric core operation and demand-based regeneration.
• Use figures from your own home: Check your water hardness and use a personalised quote and savings calculation before deciding.

Buying a water softener is not simply a matter of choosing the first system that fits your budget. The right system must suit your water hardness, household size, plumbing, pressure, available space and typical use, with clear information about salt, regeneration, installation and support.

Hard water carries calcium and magnesium minerals that leave limescale behind in boilers, kettles, taps and pipework. It can also make soaps and detergents harder to lather and rinse away. Before comparing models, use the Culligan Harvey water hardness checker to understand the water coming into your home.

Use the following 12 questions as a practical checklist. They will help you compare a twin-tank water softener, a non-electric water softener and other whole-house options on the details that affect everyday performance.

1. Is it a single-tank or twin-tank water softener?

A water softener has to soften water and periodically regenerate, which cleans and recharges the resin inside the system. The key question is what happens to your household supply while that regeneration takes place.

A twin-tank or twin-cylinder design allows one cylinder to remain in service while the other regenerates. This is how Culligan Harvey systems provide softened water around the clock. The twin-cylinder design used by Culligan Harvey is particularly useful in busy homes where showers, taps and appliances may be used at different times throughout the day.

2. Does the system need electricity?

Electricity is not inherently a disadvantage, but it changes where a system can be installed and how its controls work. An electric softener usually needs a nearby mains socket for its timer, meter or control board. A non-electric water softener uses incoming water pressure to operate the core softening mechanism.

Culligan Harvey softeners are non-electric and regenerate according to measured water use rather than relying on a fixed electrical timer. This avoids the need to position the unit beside a plug socket and reduces setup complexity. It also means the core softening process does not depend on a mains-powered control board.

Ask whether “non-electric” applies to the whole product or only the softening mechanism. For example, the HarveyArc water softener is non-electric at its core, while its optional connected salt-monitoring features use separate technology.

3. What flow rate does my home need?

Flow rate is the volume of water that can pass through the softener in a given time. It matters when several outlets run together, such as two morning showers or a shower while the washing machine fills.

Tell the supplier your bathroom count, household size and whether you use a combi boiler, unvented cylinder or other high-demand plumbing. Ask for the model’s published peak flow rate, minimum working pressure and maximum working pressure. A vague assurance that a system is “suitable for families” is not a substitute for specifications.

The HarveyArc has a peak flow rate of 56 litres per minute and is designed for homes with up to three bathrooms. Larger homes may need a higher-capacity model. The best water softener for a UK home is one sized for its actual peak demand, not simply the largest or smallest unit in a range.

4. Will it affect my shower pressure?

Flow and pressure are related, but they are not the same. Pressure pushes water through the pipework, while flow describes how much water reaches the outlet. An undersized or unsuitable component can restrict performance.

Instead of accepting a simple yes or no, ask the installer to assess the property. They should confirm the dynamic water pressure, the softener’s working pressure range, the expected flow at peak demand and whether the existing pipework or valves create restrictions. In higher-pressure homes, they may recommend a pressure-reducing valve to protect the softener and other fittings.

5. Will it fit under my kitchen sink?

A whole-house water softener does not necessarily need a large utility room. Compact models can often be installed in a kitchen cupboard near the incoming mains supply, but “fits under the sink” should never be treated as a universal guarantee.

Measure the available height, width and depth, then account for the pipework, bypass valve, drain connection and the space needed to add salt. The HarveyArc is designed to fit beneath most kitchen sinks, subject to the cupboard and plumbing layout.

Ask for a professional survey before committing to a model. An installer may find that another cupboard, a utility space or a different model gives you better access and a cleaner installation. The aim is not only to make the softener fit on installation day, but to leave enough room for easy salt loading and future service access.

6. What type of salt does it use?

Salt regenerates the resin that captures calcium and magnesium. Different water softeners may use block salt, curved blocks, tablets or granular salt, so ask which format the model requires and how easy it will be to buy, carry, store and load.

The HarveyArc uses compact Mini Curve Salt blocks designed to be easier to handle than large salt bags. Other models may use a different format, so check the exact product.

Ask how much salt the unit uses per regeneration and how often a household like yours is likely to refill it. Water hardness and consumption affect the answer. You should also confirm the required salt grade and whether using another product could affect performance or warranty cover.

7. How does the system know when to regenerate?

Regeneration should happen when the resin needs to be recharged, not simply because a date appears on a timer. A demand-based or metered system tracks water use and regenerates according to consumption and the hardness setting. A traditional timed system follows a schedule, so you should ask whether it can regenerate before the available capacity has been fully used.

Culligan Harvey’s mechanical metering system measures the water passing through the softener and triggers regeneration as required. The twin-cylinder design means one cylinder can regenerate while the other continues softening, avoiding an interruption to the softened supply.

8. What are the ongoing running costs?

The purchase price is only one part of the water softener system cost. A realistic comparison should include installation, salt, water used during regeneration, electricity where required, servicing, filters or accessories, warranty exclusions and any optional care-plan payments.

Running costs vary with water hardness, household size and usage. A family of five in a very hard water area will not refill salt at the same rate as a couple with lower consumption. Ask the supplier to explain its assumptions rather than quoting a universal monthly figure that may not reflect your home.

Culligan Harvey offers personalised quotes and several payment options for water softeners. When reviewing a quote, separate the equipment and installation cost from optional services so you can see exactly what is included. It is also worth considering the wider benefits of softened water around the home, including less limescale and easier lathering, without assuming that every household will achieve the same financial savings.

9. Can I safely drink softened water?

Ion-exchange softeners replace calcium and magnesium with sodium, so the drinking-water arrangement must be discussed during the survey. Many UK installations therefore include a separate unsoftened drinking-water outlet. This can be a dedicated tap or an arrangement that keeps the kitchen cold tap on the unsoftened supply. It is especially relevant for babies and people following a medically advised low-sodium diet.

Ask the installer what is recommended for your water hardness and household. Do not rely on a single hardness threshold quoted without context, because the sodium added depends on the amount of hardness removed. A proper installation should give you softened water where it is useful and a suitable unsoftened supply for drinking and cooking.

10. Was it designed for UK homes and water conditions?

UK properties vary considerably, from compact flats with limited cupboard space to large homes with several bathrooms. Plumbing layouts, mains pressure and water hardness also differ by region. A suitable system should have published dimensions and operating limits that allow an installer to confirm compatibility.

Ask where the softener was designed and manufactured, which boiler and hot-water arrangements it supports and whether the installer uses suitable approved components. Culligan Harvey manufactures its household softeners in Britain and its qualified plumbers install them using WRAS-approved parts.

Correct installation remains essential. Ask who will carry out the work, whether they have model-specific training and how the system will be commissioned for your local hardness.

11. What warranty and service support is included?

Read the warranty rather than relying on the number of years in a headline. Ask whether it covers parts and labour, when the cover starts, where it applies, what maintenance is required and whether the use of unapproved salt or an unsuitable installation could invalidate it.

The HarveyArc comes with a three-year manufacturer’s warranty covering parts and labour, subject to its terms. Culligan Harvey also offers optional service and ArcCare plans for eligible customers. These plans are separate from the manufacturer’s warranty and your statutory rights, so compare the included services, monthly charge, eligibility rules and exclusions before adding one.

Support is more than a warranty document. Ask who you contact for salt-ordering help, connected-app support, servicing or an engineer visit. A supplier with clear installation and aftercare routes can make ownership much simpler than a product sold without an obvious service network.

12. Can I take it with me if I move?

A water softener may be removable and reinstallable, but you should not assume it will suit the next property. It needs to be professionally disconnected, and the new home must have suitable pressure, flow, plumbing, drainage and installation space.

Ask about relocation before you buy. Confirm whether removal and reinstallation are offered, what work is excluded and whether moving the unit affects the warranty or any service plan. If your current installation includes new pipework or a separate drinking-water tap, you should also ask what will remain with the property.

Suitability must be reassessed at the new address. A model chosen for a one-bathroom flat may not meet a larger home’s peak demand, while a high-capacity unit may not fit.

Choose a water softener with clear answers

The best water softener for your home is not determined by one feature. It is the system that can meet your peak water demand, fit the available space, regenerate efficiently and come with an installation and support plan you understand.

A Culligan Harvey specialist can test your water, assess the plumbing and demonstrate the difference between hard and softened water. Book a free home demonstration to ask the questions above in the context of your property, or request a personalised water softener quote when you are ready to compare the complete cost and installation plan.

Struggling with hard water and limescale in your home? Discover why a Harvey Water Softener can be a good investment with our water softener comparison guide.

Around 70% of the UK population lives in hard-water areas, making limescale a daily reality across much of the country. The calcium and magnesium in hard water can leave deposits on taps, inside kettles and around hidden boiler components. Ion-exchange softeners remove these hardness minerals before they can form scale.

When choosing the best water softener for a hard-water area, look beyond the purchase price. Focus on the features that will affect how well the system works in your home:

• Continuous soft water: A twin-tank design keeps one cylinder working while the other regenerates.
• Efficient operation: Low salt and regeneration-water use help control running costs.
• Complete protection: The warranty should clearly state whether resin, parts and labour are covered.
• Specialist installation: The installer should assess the whole plumbing system, not simply connect the unit.
• Simple ownership: A non-electric design with no regular servicing removes avoidable appointments and components.

The British-engineered HarveyArc brings those qualities together in one compact system. It uses no electricity, supplies softened water continuously and does not require routine servicing. You simply top it up with Mini Curve salt blocks when needed.

Where Can I Compare the Best Water Softeners Side-by-Side?

All five systems below soften household water, but the ownership experience can be very different. Use the comparison to see how each model regenerates, what it consumes, the flow it supports and what maintenance you may need after installation.

_{*Specifications reflect the technical data used for this comparison. Product configurations and warranty terms can change, so confirm the final quotation before buying.}

If you are comparing the two closest non-electric twin-tank systems, the HarveyArc uses less regeneration water and has a higher published maximum flow than the Kinetico Premier Compact figures shown here. That gives you a useful balance of efficiency and performance when several showers or appliances may be running at once.

Monarch Water, BWT and Ultra Soft offer electric single-tank alternatives that may suit different budgets, spaces or flow requirements. Before choosing one, ask what happens during regeneration and whether servicing is needed to maintain the warranty.

The advertised water softener cost is only the starting point. Your full water softener system cost may also include installation, fittings, salt, regeneration water, electricity and service plans. A detailed quotation helps you compare what you will actually pay over time.

Harvey vs. Competitors: Superior Twin Tank Technology

Every salt-based water softener has to regenerate. During this cleaning cycle, brine refreshes the resin so it can continue capturing calcium and magnesium.

With a single-tank system, softening pauses while the resin regenerates. The unit usually moves into hard-water bypass, which means untreated water can enter your home for several hours. Regeneration may be scheduled overnight, but a late shower, an early washing cycle or boiler demand can still overlap with it.

The HarveyArc avoids that interruption by using two cylinders. One supplies soft water while the other regenerates, and the system switches between them automatically.

During periods of higher demand, Harvey’s parallel-flow design can also bring both cylinders into service. This helps the system deliver up to 56 litres per minute without using mains electricity.

Kinetico also offers twin-tank, non-electric technology and remains a credible premium alternative. Harvey’s advantage in this comparison is the combination of continuous operation, 17-litre regeneration and a compact design developed for British plumbing.

With BWT, Monarch Water and Ultra Soft, you need to decide whether occasional hard-water bypass works for your household’s routine.

The Industry’s Strongest Water Softener Warranty (Resin Included)

A long warranty can sound impressive, but the headline number does not tell you everything. Parts, labour, call-outs and resin may each have different terms, and some extended warranties depend on paid annual servicing.

Pay particular attention to the resin bed. It performs the ion exchange that softens your water, but chlorine and other oxidants can gradually weaken standard polystyrene resin. Some manufacturers treat this as wear and tear or exclude the resin as a consumable.

The HarveyArc warranty includes three years of manufacturer cover for parts and labour, including the resin. That period is shorter than some competitors’ headline parts terms, but its strength is the breadth and clarity of the protection. Owners know the working material inside the softener is included rather than discovering an exclusion after a fault.

Most competitor warranties in this comparison restrict or exclude resin degradation. Monarch Water and BWT offer longer parts terms, but the resin and labour conditions differ, while Ultra Soft publishes shorter standard cover. 

When comparing warranties, ask three questions: 

1. What do you have to do to keep the cover valid?
2. What will the provider repair? 
3. Who pays for the labour? 

Why Harvey’s Premium Installation Service Leads the Industry

A whole-house water softener becomes part of your plumbing system. Its installation must account for your stopcock, pipe size, water pressure, drainage, bypass valves, boiler and unsoftened drinking-water supply.

Even a well-designed softener can underperform if these details are overlooked.

Culligan Harvey uses specialists who focus on water softeners and related water systems. The process begins with a home assessment, so the recommendation reflects the property’s hardness level, peak demand, plumbing and available space. The installer then fits and commissions the system, checks the intended outlets and explains salt loading and everyday use.

This end-to-end approach keeps product advice, installation and aftercare with one team. It also helps avoid common problems such as leaving part of the home unsoftened, restricting flow or sending softened water to a drinking tap that should remain on the mains supply. The Drinking Water Inspectorate specifically advises homeowners to have softeners installed correctly and retain unsoftened water for drinking and cooking.

With a 4.6 out of 5 TrustScore from more than 14,000 reviews, Culligan Harvey gives you plenty of real customer feedback to consider. You can see what homeowners say about the softener itself, the installation experience and the support they received afterwards.

True 20-Year Lifespan with Zero Regular Maintenance

Your water softener should not create another yearly appointment to remember.

The HarveyArc runs on water pressure, so there is no plug, timer, motor or electronic control panel to programme or maintain. The system does not require regular servicing.

Your main task is simply to add Mini Curve salt blocks when the level runs low. If you are shopping for salt tablets for water softener systems, check the format your unit requires. The HarveyArc uses specially shaped blocks that are easy to handle and load through the front of the cabinet.

Harvey manufactures its non-electric softeners in Britain – making it the only UK manufacturer of non-electric systems, while many competitors rely on imports from the USA and China – and tests key components through one million operating cycles, compared with a British Standard benchmark of 4,000 cycles. That testing supports an expected working life of around 20 years when the unit is correctly installed and used as directed.

By comparison, BWT’s £215-per-year Platinum service plan is required for extended warranty cover. Scheduled support may appeal to some households, but you should include that annual fee when comparing lifetime costs.

Maximum Boiler Protection and Lower Household Bills

Limescale is easy to spot on taps, shower screens and kettles. The more expensive buildup happens out of sight, where it can coat heating elements and heat exchangers. As that layer thickens, your boiler has to work harder to heat the same amount of water. This is one of the ways hard water can damage your boiler.

The HarveyArc removes the calcium and magnesium that cause limescale before they reach your hot-water system. Because one cylinder keeps working while the other regenerates, your boiler and appliances receive soft water throughout the day rather than occasional bursts of hard water.

Over time, that continuous protection can mean less descaling, fewer limescale-related repairs and a lower risk of premature wear. You may also use up to 50% less soap and detergent because soft water lathers more easily.

The benefits can extend across the home:

• Your boiler, washing machine and dishwasher are better protected from scale buildup.
• Taps, showers, kettles and boiling-water taps are easier to keep clear.
• You spend less time and money on descaling products and heavy-duty cleaning.

Softened water works with many common heating systems, including combi boilers, when the system is installed correctly. Before installation, check the guidance for using softened water with boilers and make sure the setup suits your home.

The HarveyArc also runs without electricity. Its ongoing costs are mainly salt and the 17 litres of water used during each demand-led regeneration. Electric softeners may not use much power, but electricity, larger regeneration volumes and annual service plans can all add to the total cost over time.

To estimate your return on investment, start with the full installed price and add expected salt, water and optional support costs. Then compare that figure with what you currently spend on cleaning products, descaling, energy and limescale-related repairs.

Your exact payback period will depend on your water hardness, household size and appliance use. For many families, however, the savings can build quickly enough to recover the initial cost within a few years.

The strongest choice is the one that works with the property as a complete system. For UK households prioritising uninterrupted soft water, low regeneration use, specialist installation, clear resin cover and minimal maintenance, the HarveyArc sets the benchmark.

FAQs: Choosing the Best Water Softener for Your Household

What features should I look for when buying the best water softener for my home?

Look for twin-tank continuous flow, non-electric reliability, low water use per regeneration, a warranty that includes the internal resin and a professional installation package. Flow rate, physical dimensions and salt format should also match the home’s plumbing, demand and available storage space.

Which water softener is most recommended for a family of four?

A compact twin-tank system such as the HarveyArc is well suited to many families of four because it keeps soft water flowing during morning and evening peaks. Its maximum flow of up to 56 litres per minute can support overlapping household demand, but a home assessment should still confirm hardness, pressure, pipe size and bathroom count.

Which water softener is best suited to a smaller home or flat?

A compact non-electric twin-tank softener is a strong choice where cupboard space is limited. The HarveyArc fits beneath many kitchen sinks while retaining two cylinders, so smaller homes do not have to trade continuous soft water for a compact footprint. Flats should have an individually controllable supply and suitable drainage before installation.

How do I calculate the ROI and payback period of a water softener?

Add the installed price, salt, regeneration water, electricity and any service plan. Subtract realistic yearly savings from reduced soap and detergent use, less descaling, improved heating efficiency and fewer limescale-related repairs. Divide the remaining investment by the estimated annual saving, using conservative figures because every household’s water hardness and usage are different.