Quick answer: First confirm the problem really is low supply pressure, and contact your water company, which must meet minimum standards. If the supply is genuinely weak, the usual compliant fix is to fill a storage (break) tank from the mains and use a booster pump to pressurise the house from that tank. Fitting a pump that draws more than 12 litres a minute from the supply pipe needs your water company’s consent. Our booster pumps, such as the Speroni AKM60 and RSX(M) range, are designed to draw from a tank or private supply, not directly from the mains.
Weak showers, taps that dribble upstairs, a combi boiler that won’t fire: low water pressure is frustrating, and the obvious answer seems to be a pump on the incoming pipe. Before you buy anything, it’s worth understanding what’s actually wrong, and what the regulations allow.
Step 1: is it really low pressure?
A few quick checks rule out the common causes:
- Is the internal stop tap fully open? It’s often left half-closed after plumbing work.
- Is it every tap, or just some? One weak tap usually points to a blocked aerator, a faulty valve or undersized pipework, not the supply.
- Is it worse at certain times? Morning and evening dips can be network demand.
- Is the supply pipe old? Lead or galvanised iron supply pipes narrow over time and restrict flow.
- Do the neighbours have the same problem?
A simple jug test helps. Time how long it takes to fill a 4.5 litre container from the kitchen cold tap. According to the Consumer Council for Water, water companies report properties at risk of pressure below 10 metres head (1 bar) at a flow of 9 litres per minute, which is filling a 4.5 litre container in about 30 seconds. The guaranteed minimum is 7 metres static head (0.7 bar) in the communication pipe. If you’re below those, call your water company first. Checking is usually free, and the problem may be theirs to fix.
Step 2: why you can’t just pump the mains
This is where many people go wrong. Under the Water Supply (Water Fittings) Regulations 1999, installing a pump or booster that draws more than 12 litres per minute, connected directly or indirectly to a supply pipe, requires you to notify the water company and get consent before work starts (unless an approved contractor carries it out).
There are good reasons for this. A pump on the mains can pull pressure away from your neighbours, and it can increase the risk of water being drawn back into the public supply.
The pumps we sell for boosting are built for clean water from a tank or private supply. They are not WRAS approved and must not be connected directly to the mains.
The tank-fed booster set-up
The standard arrangement looks like this:
- Mains supply feeds a cold water storage tank through a float valve, with an air gap so stored water can’t flow back into the mains.
- The tank acts as a buffer. The mains refills it slowly; the pump draws from it as fast as the house needs.
- A booster pump draws from the tank.
- Pressure control, either a pressure switch and pressure vessel or an electronic pressure controller, starts the pump when a tap opens and stops it when it closes, with dry-run protection.
- The house gets steady pressure, regardless of how weak the incoming supply is.
The same principle applies to private water supplies and boreholes, where the pump fills or draws from a storage tank.
Choosing a booster pump
Two designs cover most domestic and light commercial boosting.
Peripheral pumps: compact, steady pressure
A peripheral pump builds high pressure from a small motor, with modest flow. The Speroni AKM60 gives up to 40 L/min and up to 40 metres of head, and it is self-priming to 7 metres, so it can sit above the tank. Its stable pressure curve suits small pressure vessels and simple systems: a small home, an annexe, a cabin, or a handful of outlets.
Add a pressure controller and the AKM60 becomes a simple booster unit that starts when a tap opens.
Multistage pumps: more flow, quieter running
A horizontal multistage pump stacks several impellers, each one adding pressure. The Speroni RSX(M) range is 304 stainless steel throughout the wetted parts:
- RSX(M)2: up to 80 L/min, up to 55m head (4, 5 or 6 stages)
- RSX(M)4: up to 180 L/min, up to 60m head, for larger houses, several bathrooms or light commercial use
The “M” means 230V single phase; no “M” means 400V three phase. The RSX(M) is not self-priming, so it works best with the tank level with or above the pump (flooded suction), or with a foot valve.
The difference between these designs is covered in more depth in self-priming, peripheral and jet pumps explained and how submersible pumps work, which explains multistage impellers.
How to size a booster pump
You need two numbers: flow and head.
Flow. Work out which outlets are likely to run at the same time. As a rough guide, a shower uses around 9 to 12 litres per minute and a kitchen tap 4 to 6. Two showers and a tap running together is around 25 to 30 L/min.
Head. Add together:
- the height from the pump to the highest outlet, in metres;
- the pressure you want at that outlet (1 bar is 10 metres, so 2 bar is 20 metres); and
- an allowance for pipe friction.
Then look at the pump curve, not the maximum figures. A pump’s maximum head is at zero flow, and its maximum flow is at zero head. You need a pump whose curve passes through your flow at your head. Our guides to how head height equates to pressure, high flow vs high head and how to read a pump curve walk through it.
Installation
A booster set must comply with the water fittings regulations, so have it installed by a competent plumber, ideally one on an approved contractor scheme, and the electrical connection made by a qualified electrician. Mount the pump on anti-vibration feet, keep it dry and ventilated, and fit isolation valves so it can be serviced.
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