How to eliminate a water hammer after flushing a toilet

Updated February 21, 2017

New quick-closing toilet fill valves can cause water hammer situations in many plumbing systems. Ways to eliminate water hammer after flushing a toilet include installing a permanent water hammer arrester at the toilet supply, installing a whole house bladder tank at the water heater or individual fixture arresters in several locations throughout the home. Installing a small, pressure-absorbing bladder tank on the cold water supply of the home's water heater is the best solution. Installing the tank will require some plumbing skill. The experienced do-it-yourselfer should have no problem with the pipe connects required.

Turn the main water supply off to the water heater, either at its individual fixture cut-off or at the main house supply.

Cut the copper supply pipe with tubing cutters in a horizontal location. Sand the pipe ends and fittings with emery cloth. Coat the outside of the pipe and inside of the fittings with flux; use a small acid brush. Install a tee fitting facing up. Cut a 2-inch piece of copper pipe and insert it into the top of the tee, and then slip on a female adaptor. Solder all the joints with a torch and lead-free solder. Wipe the joints clean with a rag and allow them to cool.

Wrap thread tape around the male threads of the pressure tank several time to insure a watertight connection.

Screw the tank onto the fitting by hand.

Turn the water back on and check for leaks.


Always install the tank between the fixture cut-off and water heater. Installing the tank vertically is always the best choice. The bladder tank should be preset to an adequate pressure; however, adjustments my need to be made.


Not following the manufacturer's instruction could cause personal injury and property damage.

Things You'll Need

  • Tubing cutter
  • Emery cloth
  • Flux
  • Acid brush
  • Copper fittings
  • Bladder tank
  • Thread tape
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About the Author

Kelly Schuler is both a writer and a plumber. He self published "Plumbing Do's and Dont's" in 1999. Schuler has been a licensed plumbing and gas-fitting contractor since 2001 and a licensed journeyman plumber since 1986. He actively owned and operated his own plumbing and gas fitting business from 2001 to 2008.