In short
Sudden low water pressure in a commercial building is usually caused by a failed booster pump or booster set controller, a tripped supply, a closed or failed valve, a low cold water storage tank, or an incoming supply problem. Check whether the whole building or only upper floors are affected and whether the booster set shows alarms, then call a commercial engineer.
Is it urgent?
Call now if
- Upper floors or the whole building have lost water
- Toilets, kitchens or process equipment cannot operate
- The booster set has failed with all pumps in fault
- Water is leaking from the booster set or tank room
Usually suitable for scheduled work
- Slightly reduced pressure at a few outlets
- Booster pumps cycling more often than usual but supplying water
- Planned booster set replacement or water tank works
Loss of water pressure in commercial buildings
Many commercial buildings store cold water and use booster sets to deliver it at usable pressure to upper floors and outlets. When pressure fails, the cause is usually in that plant rather than the public supply.
Domestic supply problems versus commercial plant
| Situation | Likely responsibility |
|---|---|
| No water anywhere, neighbours affected | Water supplier’s network |
| Mains-fed ground floor fine, upper floors dry | Building booster set or storage |
| Booster set alarming or all pumps stopped | Building plant: call an engineer |
| Low cold water tank level | Float valve, supply or leak in the building |
Booster pump failure
Booster sets usually have two or more pumps with a controller that starts them as demand rises. Failure of the controller, pressure sensor or all pumps stops the supply. See commercial pump repairs.
Relevant pumps and controls
Pressure transducers, variable speed drives, pressure vessels and low-level protection on the tank all affect booster operation. A failed low-level switch can stop pumps to protect them from running dry.
Building-wide disruption
Loss of water affects toilets, kitchens, cleaning, process equipment and sometimes fire suppression or humidification systems. Consider closing affected facilities and informing occupants.
Safe inspection and isolation considerations
Do not open booster set control panels or adjust pressure settings. Panels contain live parts, and incorrect pressure settings can damage pipework and fittings.
Professional repair requirements
An engineer will check supply, tank levels, controls, sensors and pumps, restore supply where possible and arrange repairs. Water hygiene measures should be followed when the system is restored.
Water Pressure Failures: frequently asked questions
What can cause a commercial building to lose water pressure?
Common causes include booster pump or controller failure, a tripped electrical supply, low water in the cold water storage tank (for example from a failed float valve), closed or failed isolation valves, leaks, and problems with the incoming mains supply. Pressure loss only at upper floors usually points to the booster set.
How do we know if it is our booster set or the mains supply?
If ground-floor outlets fed directly from the mains are also affected, the problem may be the incoming supply, so check with your water supplier for local outages. If only boosted outlets or upper floors are affected, the booster set or storage is the likely cause.
Is low heating system pressure the same as low water pressure?
No. Heating systems are usually sealed circuits kept at pressure by a pressurisation unit. Low heating pressure affects boilers and heating, not taps. See pressurisation unit repairs.
Are there water hygiene issues after a booster failure?
Possibly. Interruptions, stagnation and work on cold water systems can affect water quality. Your legionella risk assessment and water hygiene arrangements should be followed when the system is restored.
Do you deal with public water main bursts?
No. Problems with the public water main are the responsibility of the water supplier. We deal with commercial plant and pump systems inside the building.
UK guidance and references
Primary and industry sources relevant to this subject. Always check the current edition and how it applies to your building.
- Legionnaires' disease (ACOP L8) Health and Safety Executive
- Water Supply (Water Fittings) Regulations 1999 legislation.gov.uk
- Electrical safety at work Health and Safety Executive