Why do your pipes bang?
Search it and you will be given two fixes. One is to clear the air chambers, and the other is to turn the pressure down at the regulator.
Plenty of houses here have neither of those fittings. Both pieces of advice send you looking for something that was never installed, which is why the noise is still there after an afternoon in the ceiling.
When it bangs tells you most of it
- The moment a tap or valve shuts One knock, straight after. Moving water stopped suddenly.
- While the washing machine fills Its valve closes fast by design. The machine is not the fault.
- Every time the pump cuts in or out That points at the pump side, and part of it is not a plumber's work.
The two fittings page one assumes you have
An air chamber is a short capped pipe built in above a tap, holding a pocket of air for the shock to push into. They are ordinary in American plumbing and they are not ordinary here. If yours was not built with them, there is nothing to drain and nothing to clear.
The second fix is to lower the house pressure, which page one usually puts at somewhere between forty and sixty psi. That assumes a regulator on the incoming line to lower it with. Most houses here do not have one, which is the same correction that catches people out when their pressure is weak rather than noisy.
Low water pressure, and the screw everyone tells you to turn
Where the push comes from in a house like yours
If your water reaches the taps through a tank and a pump, the pressure in your pipes is made by that pump and not by the street. That is not an accident of how your house was built, it is the lawful arrangement: a pump may not be connected straight onto a public main, so the line fills a tank and the pump draws from the tank.
The rule that puts the tank there, quoted in full
So the bang usually starts on the pump side. A pump cutting in and out, a check valve slamming as it stops, or, most often of all, a run of pipe with nothing clamping it to anything. That last one is why the noise so often seems to come from inside a wall: the pipe is free to move, and it moves against whatever it is resting on.
What you can find out tonight, for nothing
Close the taps and listen to where the knock is, then have somebody shut a tap while you rest a hand on an exposed pipe run. A pipe you can feel jump is a pipe that is not held, and that is a clip rather than a job.
Then try it with the pump switched off and the tank feeding by gravity, if your setup allows it. If the banging stops, you have narrowed it to the pump side without paying anybody to tell you so.
A bang that has only started recently is worth a look. The shock that makes the noise is working on every joint it passes, and the joint that gives way will be one you cannot see.
What we would do about it
Find which run is moving and clamp it, and put a proper arrestor where a fast-closing valve needs one rather than everywhere. Where the pipework itself is the problem, that is a line repair.
Where it stops being ours
If the pump is switching on and off rapidly, the usual cause is the pressure tank rather than the pipes, and the electrical side of a pump is an electrician's work. Tell us that is what it is doing and we will say so before anybody comes out, which is cheaper for you than finding out afterwards.
Where this comes from
The rule that puts a tank between the main and the pump is the Department of Health's Supplemental Implementing Rules and Regulations of Chapter II, Water Supply, of the Code on Sanitation of the Philippines, section 4.3.1(d). It is quoted in full on the booster pump page rather than paraphrased twice.
The forty to sixty psi figure is quoted only as what the articles on page one recommend, read on 26 September 2026. It is evidence about those articles, not a setting to aim at, and this page does not suggest anyone go looking for a dial.
Questions about banging pipes
- What is the banging when I turn off the tap?
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Water that was moving has been stopped suddenly and the momentum has nowhere to go, so it hits the inside of the pipe and the pipe moves. The proper name is water hammer. It is not the pipe being weak, it is the pipe being pushed.
- Every guide tells me to clear the air chambers. Where are they?
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Most likely nowhere. Air chambers are short capped pipes built in above the taps to give the shock somewhere to go, and they are standard in American plumbing rather than here. If your house was not built with them, there is nothing to clear and no amount of looking will produce one.
- And the advice to turn the pressure down?
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That assumes a pressure regulator on the incoming line, which most houses here do not have either. It also assumes the pressure is coming from the street, and if your water reaches the house through a tank and a pump, the pressure is coming from your own pump instead.
- So where is it coming from in my house?
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Usually the pump side. A pump that cuts in and out, a check valve slamming shut when it stops, or a length of pipe with nothing holding it to anything. The last one is the commonest and the cheapest to put right, and it is why the noise often sounds like it is coming from inside a wall.
- Is it doing any harm, or is it just noise?
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It can do harm. The same shock that makes the noise works on every joint it passes, and the ones that go are the ones you cannot see. A bang that has appeared recently is worth looking at rather than living with.
- It bangs when the washing machine fills. Is that different?
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Same cause, and the machine is not at fault. A washing machine valve closes fast by design, which is exactly the sudden stop that starts it. The fix is on the plumbing side, not in the appliance.
- The pump switches on and off rapidly and it bangs each time.
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Tell us that, because it changes the answer. Rapid switching is usually the pressure tank rather than the pipework, and the electrical side of a pump is an electrician's work rather than ours. We would rather say so than take the visit.
If you would rather text
A written message reaches us with the detail already in it, so we know what is wrong before we ring you back. If you would rather send it as a text, the number is on the contact page.
Monday to Sunday, 8AM–8PM
Emergency Repairs Available 24/7
Banging that has only just started?
Say when it happens and whether you are on a tank and pump. If it turns out to be the pump's electrics, we will tell you that instead of sending somebody.
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