Water Softener vs. Water Filter: Key Differences, Total Savings & Do You Need Both?

In summary

A water softener removes hard minerals from your home’s mains water supply, while a water filter removes impurities and contaminants from your drinking water. The purpose of a water softener is to prevent limescale from building up in your boiler, heating system and appliances. A water filter, on the other hand, improves the taste and quality of the water you drink.
You can use both a water softener and a water filter together for whole-home protection. For example, pairing a non-electric Culligan Harvey twin-tank softener with an under-sink drinking water filter can raise your overall water quality, protect your home’s systems and improve soap lathering.

What Makes the Best Water Treatment System? The best water treatment system depends on your specific water needs:

• Choose a water softener if your main issue is hard water and limescale build-up affecting your boiler, pipes, and appliances.
• Choose a water filter if you want to remove contaminants, chlorine, and impurities to improve the taste and quality of your drinking water.
• Choose a combined system (water softener + water filter) for the best overall solution, offering whole-home limescale protection along with purified, great-tasting drinking water at the tap.

What is a water softener?

A water softener is an appliance that connects to your water supply and removes minerals such as calcium and magnesium. Without a softener, these minerals can create limescale, a chalky crust that can damage your boiler, radiator, shower head, or kettle. Softening your water at the main line can provide whole-home limescale protection. 

Culligan Harvey water softeners use an ion-exchange system to provide continuous treatment. Each unit has two cylinders that are filled with negatively charged resin beads. As the water flows through the cylinder, these tiny beads attract positively charged magnesium and calcium particles and remove them from the water.

Once a cylinder has collected enough hard minerals, it automatically starts a process called regeneration. The softener uses a sodium brine solution to clean the magnesium and calcium off the beads and flush these minerals into your wastewater system.

While one cylinder is regenerating, the other continues to soften your water, ensuring a 24-7 supply. And because the system operates using only the flow of water, it doesn’t consume any electricity.

British-engineered Culligan Harvey softeners have a 50% salt efficiency. They use approximately 300g of salt and 17L of water per regeneration — significantly less than imported models, which often use more than 400g of salt and up to 24L of water.

What is a water filter?

A water filter removes tiny particles from your drinking water before it flows out of the tap. Many models use activated carbon filters to trap impurities such as chlorine, organic compounds, and pesticides. Some models also feature reverse osmosis technology to push water through a membrane with microscopic holes, leaving behind contaminants such as heavy metals and other dissolved solids.

By removing impurities and contaminants, a water filter creates pure, fresh-tasting water from your taps. However, it can’t remove calcium and magnesium, which means it doesn’t protect your plumbing, shower heads, or boiler from limescale.

Side-by-side comparison: Softener vs. filter

Can you use a water softener and water filter together?

You can use a water softener and a water filter together to prevent limescale and improve water quality throughout the whole house. Typically, you’d connect a softener at the mains entry point and put a water filter under your kitchen sink. The water softener treats hard water before it reaches your plumbing and major appliances, while the filter treats your drinking water.

Installing a softener before the water filter can protect your appliances and help extend the lifetime of the filter. Softened water prevents limescale from clogging your filters and reverse osmosis membranes, so they last longer.

Concerned about the additional sodium in softened water? While the sodium level is quite low, you can also install a dedicated drinking water tap that bypasses the softener and runs through a filter. This strategy ensures optimal taste and purity for cooking, infant formula, and hot drinks while keeping sodium levels in check.

Which system does your home need?

Use these tips to determine whether you need a water softener, a water filter, or both.

Choose a water softener if:

• You see a chalky limescale crust on your kettle, taps, or shower screens
• Your heating bills are rising steadily
• Your boiler requires frequent repairs related to limescale
• You have difficulty lathering soap in the sink or shower
• You have dry skin or dull hair

Choose a water filter if:

• Your tap water has an unpleasant taste or tastes metallic
• Your tap water smells strongly of chlorine
• You want to drink tap water and eliminate expensive single-use plastic water bottles

Choose both if:

• You live in a hard water region, such as south, east, or central England
• You want complete protection against home limescale and pure, restaurant-quality drinking water

Complete water control for your home

A water softener provides whole-house protection from limescale, while filters treat your drinking water, ensuring it’s pure and fresh-tasting. By combining both water-treatment technologies, you can create the ultimate system that improves your water quality and extends the lifetime of your boiler, pipes, and major appliances.

Key takeaways

1. Distinct functions: Water softeners prevent limescale across your whole home; water filters improve the taste and purity of your drinking water at the tap.
2. Dual-system synergy: Combining a Culligan Harvey non-electric softener with an under-sink filter protects your home and delivers pure drinking water.
3. Superior efficiency: Culligan Harvey’s twin-tank softener technology uses zero electricity, delivers 50% better salt efficiency, and uses less water for regeneration than imported systems, keeping operational costs low.

Frequently asked questions

Does a water filter soften water?

No. A water filter typically removes contaminants and impurities to improve the taste of the water, but it doesn’t remove the calcium and magnesium particles that cause limescale.

Can you drink softened water?

Yes, softened water is safe to drink for most people. However, many homeowners prefer a dedicated filtered drinking tap to deliver pure, fresh-tasting water for drinking and cooking.

Do I need both a water softener and a water filter?

If you want both limescale protection and high-quality drinking water, using a water softener and a water filter together can provide the most complete solution.

What comes first, a water softener or a water filter?

Typically, the water softener comes first at the main supply, while the drinking water filter is located at the point of use (often, the kitchen sink).