Low Water Pressure?

Local Water Supply

Our area is primarily served by Southern Water (Andover SP10/SP11, Stockbridge SO20) and Thames Water (Marlborough SN8, Hungerford RG17). Water is sourced from chalk aquifers, which means it's very hard — great for mineral content, problematic for plumbing longevity.

Rural villages like Great Bedwyn, Ramsbury, Shalbourne, and Upper Clatford often have longer supply runs from the water main, which naturally reduces pressure. Properties at higher elevations in Tidworth (SP9), the Wallops, and Pewsey (SN9) are particularly susceptible.

QWhat's the difference between water pressure and water flow?

Pressure is the force pushing water through the pipes (measured in bar). Flow is the volume of water coming out (measured in litres per minute). You can have good pressure but poor flow if your pipes are narrow. And you can have good flow but poor pressure if the supply is high-volume but low-force. Most problems are actually flow issues disguised as pressure problems. A plumber can test both to determine the real cause.

QMy combi boiler shows low pressure - is this the same thing?

No! Combi boiler pressure (shown on the gauge, usually 1-2 bar) refers to the sealed central heating system pressure, not your mains water pressure. If your boiler gauge drops, you need to repressurise the heating system using the filling loop. This has nothing to do with your taps or shower pressure. If your shower is weak with a combi boiler, the problem is either low mains pressure (needs a booster) or the boiler's hot water output is limited.

QIs low water pressure dangerous?

Low pressure itself isn't dangerous, but it can indicate problems that are. A sudden pressure drop could signal a burst pipe. Consistently low pressure can prevent fire suppression sprinklers from working properly. Low pressure can also cause air locks in heating systems and prevent some safety devices from functioning. While not an emergency, persistent low pressure should be investigated.

QI'm renting - who's responsible for fixing low water pressure?

If the problem is with the water company supply (below minimum standards), the water company must fix it regardless of whether you rent or own. If the problem is internal plumbing (pipes, stopcock, PRV), your landlord is responsible for maintaining the property's plumbing to a reasonable standard. Document the issue, report it to your landlord in writing, and reference the Homes (Fitness for Human Habitation) Act 2018 if they don't act.

QWhat are the water company's obligations for pressure?

Under Ofwat regulations, your water company must provide a minimum of 1 bar static pressure at the boundary stop tap (the point where their pipe meets yours). This equates to roughly 10 metres head of water. If they consistently fail to meet this, you can request a pressure test and they must resolve it. You may also be entitled to compensation under the Guaranteed Standards Scheme (GSS). In our area, Southern Water and Thames Water are the main suppliers.