What a softener installation needs: space, drainage and regulations

The hard tap, which is not optional

The Water Supply (Water Fittings) Regulations require that a supply of unsoftened water is available for drinking and food preparation. In practice that means the kitchen cold tap is taken off the rising main before the softener.

There are three reasons this matters:

• Sodium. Softened water contains added sodium in proportion to the hardness removed. For most people that is not significant; for anyone on a sodium-restricted diet, and for making up infant formula, it is.
• Other uses. Softened water is not suitable for filling a fish tank and is not ideal for certain plants.
• Compliance. An installation that softens every outlet including the drinking tap does not meet the requirement.

Position

Where it goes is determined by four things at once, and all of them have to work.

1. Access to the rising main, after the incoming stopcock, so the whole house is treated.
2. A drain connection within reach, which is frequently the binding constraint.
3. Access for salt, which people consistently underestimate. A softener in an awkward corner is a softener that does not get topped up.
4. Space and a level base capable of taking the machine with a full brine tank, which is heavier than it looks.

Frost deserves a specific warning. A softener in an unheated garage or outbuilding contains a substantial volume of water and can freeze, which damages the valve and the pressure vessel. If the position is unheated, it needs protecting.

Drainage and the air gap

Regeneration discharges brine and flushed hardness to drain. Two requirements:

• Adequate flow capacity. The discharge happens at a reasonable rate and the drain must take it without backing up.
• A proper air gap. The discharge must not be directly connected to the drain in a way that could allow backflow into the softener. A physical air break – a tundish arrangement or an appropriately designed connection – is required. This is a backflow prevention requirement and it is the detail most often skipped in a DIY installation.

The drain run should also be as short and as free-falling as practical. A long horizontal run or one with a lift needs care, and some machines specify a maximum discharge run length above which performance suffers.

There may also be an overflow requirement from the brine cabinet, which should discharge somewhere visible so a fault is noticed.

Bypass, isolation and the rest

1. A bypass valveSo the softener can be taken out of service without shutting the house off. Essential for servicing and for the occasion when something goes wrong. Most machines come with one; it needs to be accessible.
2. Isolation either sideSo the unit can be removed entirely.
3. A power supply for metered unitsA standard socket, reachable, and ideally not shared with something that gets switched off.
4. Correct connection to the rising mainAfter the stopcock, after the hard tap take-off, before everything else.
5. Pressure considerationsSofteners have a minimum and maximum working pressure. Where mains pressure is very high, a pressure reducing valve may be needed; where it is marginal, the pressure drop across the softener matters.
6. CommissioningThe unit set up with your actual hardness figure and household size, run through a regeneration, and the softened output tested.

Things that are frequently got wrong

1. The drinking tap softened. The most common non-compliance.
2. No air gap on the drain, or a direct connection into a waste.
3. No bypass, or one that is inaccessible behind the machine.
4. Installed before the stopcock, or teed in somewhere that leaves part of the house untreated.
5. Outside tap softened, which wastes salt for no benefit – garden water does not need softening.
6. Set up on factory defaults rather than your actual hardness, so it over- or under-regenerates.
7. Sited where nobody can load salt without emptying a cupboard.
8. Frost exposure in an unheated position.

None of these stop a softener working immediately, which is why they persist. They show up as excess salt use, non-compliance, or a machine that cannot be serviced without draining the house.