Water Pressure
City pressure reliably reaches about six stories. Everything above that is being lifted by something, and when the pressure goes it is usually that something.
How water gets to a high floor in New York
Street pressure alone will fill a building to roughly six floors. Above that, a building needs help, and in Manhattan it is nearly always one of two arrangements.
| Roof tank | A pump fills a tank on the roof, and the tank feeds the building by gravity. Steady pressure, and the reason the wooden tanks are on the skyline |
|---|---|
| Booster pump | A pump set in the cellar pressurises the risers directly. More common in newer conversions and smaller buildings |
Knowing which one your building has tells you where to look on the day the pressure drops, and it is the first question worth asking the super.
Pressure everywhere, or pressure in one place
The whole building, all at once
Tank or pump. A failed fill pump, a stuck float, a tripped breaker, or a booster that has lost its pressure switch. This is building equipment and the managing agent needs to know.
Only the top floors
Normal behavior taken one step too far, or a tank that is not filling to its proper level. The top floor always has the least head, so it is where any shortfall appears first.
One apartment, everything in it
The branch feeding that apartment, or the valve where it leaves the riser. Old gate valves seize part-open and throttle a whole unit without ever fully failing.
One fixture
Aerator, cartridge or stop valve. Ninety per cent of single-fixture complaints are solved at the fixture, and it costs nothing to check before anyone looks further.
Hot weak, cold fine
Almost always scale, either in the heater or in the hot run. Hot water lays down deposit faster. See water heaters.
Pressure that is too high
The opposite problem is real and does more damage than people expect. Excess pressure shortens the life of every valve, connector and appliance hose in the apartment, and it is a common cause of the burst flexible lines that flood kitchens. A pressure reducing valve, set correctly and checked occasionally, is inexpensive insurance. They do drift as they age, so a reading is worth taking if yours has been in a long time.
What we measure
- Static pressure at a fixture, and again with fixtures running, which separates a pressure problem from a volume problem
- Behavior at different heights in the building
- Whether hot and cold differ
- The condition of the supply piping, because a scaled pipe delivers volume like a narrow pipe no matter what the gauge says. See repiping
Need this doing?
Call and describe the problem. You will get the price before anyone starts.