How Do I Fix Noisy Pipes?

Noisy pipes are a nuisance! Before you can fix the problem, you need to determine the cause. Water hammer, air in the pipes, under-sized water meters, and water pressure set higher than 60 PSI are just some of the contributors to noisy pipes.
Water Hammer in Pipes

Is it water hammer or air in the pipes?

If the noise starts when you open a faucet or valve, most likely you have air in your pipes. If however the noise starts when you close the valve, it’s probably water hammer. And just to make things interesting, if the noise happens when your pump starts, it could be both.

 These are signs of water hammer:

  • The noise happens when the valve closes.
  • The noise happens when the pump starts.
  • The noise consists of quick, repeated bumps or a loud thump followed by silence.

These are signs of air in the pipes:

  • The noise has nothing to do with opening or closing a valve or faucet.
  • The noise happens when the pump starts.
  • The noise consists of vibrating or other prolonged sounds.

How to Fix Water Hammer

  • The simplest fix is lowering water pressure for the entire irrigation system. This may not get rid of water hammer completely, but may bring it down to a tolerable level.
  • Another way to fix water hammer is to change the order in which the valves operate. First, figure out which valve uses the least water; this is likely the valve with the least number of sprinklers. Once you found it, rewire the controller so that valve is the last one to run.
  • You can also use a water hammer arrestor. Typically, these only work with water hammer caused by laundry machines and dishwashers; however, it’s worth a try for water hammer from your automated irrigation system. Follow the manufacturer instructions for installation and put it on a hose bib  at the point where the irrigation system connects to the house water. Even better, if there’s a hose bib on the irrigation system mainline, install it there. You can also tap into the irrigation mainline to install it. If the water hammer arrestor doesn’t work, you can remove it.
  • Your valve might be too small. If this is the case, reduce the water velocity by:
    • Replacing the valve.
    • Split the valve zones. If the water hammer is caused by just one valve, the quickest fix is to reduce the amount of water that valve uses. Ultimately, this reduces the water velocity and stops water hammer. After you do this, you’ll have to reduce the number of sprinkler heads that valve operates. This is easy – just install a second valve and connect half the sprinklers in that zone to the second valve.
    • Look for “bottlenecks.” Bottlenecks are areas of pipe that are smaller than others. Areas you want to check include the gooseneck, the house water supply pipe, and the irrigation mainline. Once you find an area that is smaller than the others, replace it with a larger pipe. Determining pipe size is simple. Take a piece of string approximately 6 inches long and measure the number of inches of string necessary to go around the pipe once. This is the pipe circumference. Use the chart below to find your pipe size by looking for the circumference.
For Copper and PEX Tube and Pipe (Hancor, JDS, JM Eagle)
Circumference Pipe Size
2.75″ (70mm) 3/4″ pipe
3.53″ (90mm) 1″ pipe
4.32″ (110mm) 1 1/4″ pipe
5.10″ (130mm) 1 1/2″ pipe
For Steel Pipe or PVC Plastic Pipe (Hancor, JDS, JM Eagle)
Circumference Pipe Size
3.25″ (83mm) 3/4″ pipe
4.00″(102mm) 1″ pipe
5.00″(127mm) 1 1/4″ pipe
6.00″(152mm) 1 1/2″ pipe
For Flexible Polyethylene Pipe (Hancor, JDS, JM Eagle
Circumference Pipe Size
2.96-3.33″ (75-85mm) 3/4″ pipe
3.74-4.24″ (95-108mm) 1″ pipe
4.90-5.57″ (124-141mm) 1 1/4″ pipe
5.70-6.28″ (145-160mm) 1 1/2″ pipe

How to Fix Air in Pipes

A good method of removing air from pipes is increasing the water speed and forcing the air out.

  • Create a high water demand by turning on as many water outlets as possible. The high water velocity will force the trapped air out of your pipes.
  • If you need to increase water velocity in a mainline, you need to manually open two or more of the circuit valves. Keep the water running to force out the air. Close the valves one at a time to avoid a pressure surge that could damage your irrigation system.
  • When increasing water velocity in lateral pipes, you need to remove some of the sprinklers from the valve circuit. Find and remove the three sprinkler heads that are the furthest from the circuit valve. Then open the valve to flush out the air. If this doesn’t work, remove more sprinkler heads. Put the sprinkler heads back on once the air is out of the lines. If this doesn’t solve the problem, your sprinkler heads might be at different heights which can cause water to drain out of the pipes through the sprinkler heads, allowing air in. To fix this, you must install check valves (include these?) at the inlets of your sprinklers; check valves don’t affect your sprinklers, they just push water back to prevent draining. Many manufacturers provide sprinklers with built-in check valves.
  • One last place to check is your household pipes. If there is air in these lines you need to turn on all of the faucets and flush all of the toilets in your house. Give the air a few minutes to move out of the lines and then turn off your faucets one at a time, beginning with the one closest to where the water supply enters your home. As you work your way through your house, flush each toilet again and wait two minutes before you close the next faucet.