Okay, So I am beginning to get concerned. The sump pump in our basement works great but every time it relieves water there is a huge banging in the pipes after the pump turns off. It was suggested that I put a water hammer T in the pipe exiting the home. I have not been able to find much online about water hammering in drain pipes. I have found a lot on water pipes though. Is it the same concept?

Exactly the same. The idea is to creat a pocket of air, because, ais is compressible. It’s like squeezing a
baloon. Water is not compressible, and is like squeezinc a rock- no give. When water in motion is stopped suddenly, it wants to keep going. Putting the air cushion in the line allows it to stop gently.

Check to see if the sump outlet pipes are rubbing against, hitting or bumping into anything. What you have could be called hydraulic jump. When the pump shuts off you get a type of hydraulic bump from the water setting down. Perhaps even hold onto the pipe and see if you can determine where the noise is emanating

Not sure a water hammer will work for you, since your pumping water into a drain pipe which is not under pressure, but free flowing. Can you locate where the noise is coming from? It might be the pipe is hitting something.

This sounds really weird to me. Water hammer happens in house water lines because they whole thing is under pressure – From the water line from the street to the pipes in your house, with no air in the in to cushion the shock wave. A sump-pump drain line isn’t under pressure however – It’s just water flowing in a pipe. Any ‘shock waves’ (water hammers are caused by shock waves travelling in the pipes) would just dissipate in the sewer pipe because there’s lot of air in there.

I know some sump pumps can be backup-powered by the water pressure in your home. This prevents a flood in a power failure. Is your pump powered by house water pressure? Is that the hammer you’re hearing?

When a sump pump shuts off, there is a check-valve to prevent the water still in vertical piping from flowing back to the sump, and there is the weight of the water in the pipe, and (possibly the torque of the motor on the pump/ piping); any of these might cause movement of the discharge piping and cause noise, or just the check-valve closing might cause noise. Check for proper/ secure mounting of the pipe, rubbing against another pipe or wall.