A weak shower or a bath that takes twenty minutes to fill is one of the most common calls we get, and the cause is often something you can find yourself in ten minutes. Brighton adds its own complications: hilly streets, converted Victorian terraces with pipework from three different decades, and some of the hardest water in the country. Here is how to work out what is actually going on before you pay anyone to look at it.
These get used interchangeably, but they are different problems with different fixes. Pressure is the force pushing the water, measured in bar. Flow is how much actually arrives, measured in litres per minute. You can have perfectly good pressure at the boundary and still get a trickle upstairs because a pipe somewhere has silted up.
A rough test costs nothing. Put a measuring jug or a bucket under the cold kitchen tap, run it full bore for six seconds, and multiply what you collect by ten. Under about 10 litres per minute at the kitchen tap suggests a genuine supply or blockage problem. Between 10 and 20 is workable but will feel disappointing on a mixer shower. Over 20 and your problem is almost certainly downstream, in one specific fitting or appliance.
Start by asking whether the problem is the whole house or just one outlet. If it is one tap or one shower, you have a local fault and nothing to worry about on the supply side.
Limescale is the headline. Southern Water supplies this area from the chalk aquifer, so hardness typically sits around 250 to 300 mg/l as calcium carbonate. Over fifteen or twenty years that narrows the bore of pipes and blocks cartridges, thermostatic shower valves and combi heat exchangers.
Old pipework is the other big one. Plenty of terraces in Hanover, Kemptown and Preston Park still have a 15mm lead or galvanised steel supply pipe rather than a modern 25mm plastic main. Galvanised steel corrodes internally and can lose half its bore. Replacing the supply from the boundary to the house typically runs into four figures once you include excavation and reinstatement, so it is worth confirming the diagnosis properly first.
Height matters too. If you live partway up Elm Grove, Dyke Road or in a top floor flat in a converted house, you are working against gravity, and every metre of height costs you roughly 0.1 bar. Flats also often have a shared rising main or a pressure reducing valve set too low, which is a cheap fix if you can identify it.
Finally, if you have a loft tank feeding your hot water rather than a combi boiler, low pressure upstairs is normal physics, not a fault. A tank in the loft gives you very little head at a first floor shower. A pump or a change of system is the answer, not a repair.
Southern Water has a statutory duty to provide a minimum of 7 metres of static head at the boundary stopcock, which is roughly 1 bar, at a flow of 9 litres per minute. If you are below that, report it and they will test it, usually free of charge. Everything from the boundary into your house, including the supply pipe under your own garden, is yours to maintain.
Sudden drops across a whole street are usually a burst or planned work, and Southern Water's website lists current incidents by postcode. Gradual decline over years points at your own pipework or scale.
A proper investigation means gauging static and dynamic pressure at the stopcock and at the affected outlet, timing flow at several taps, and isolating sections to find where the loss happens. That usually takes an hour or two and tells you whether you need a 50 pound cartridge, a descale, a pump, or a new supply pipe.
Be wary of anyone recommending a booster pump before measuring. Fitting a pump to a mains supply without the right accumulator or approval can breach water regulations and can pull pressure from neighbours, and it does nothing at all if the real problem is a blocked pipe.
Those are peak demand times across the network, so pressure at your boundary genuinely dips. If your supply is already marginal, a normal drop of 0.2 to 0.3 bar is enough to turn an adequate shower into a poor one.
It will stop the problem getting worse by preventing new scale, but it will not clear deposits already in your pipes and cylinder. In a hard water area like Brighton it is a sensible long term investment alongside, not instead of, fixing the current fault.
No, that gauge shows the sealed central heating circuit, which is separate from your tap water. If it reads below about 1 bar you need to top it up using the filling loop, and if it keeps dropping you have a leak or a failed expansion vessel.