I am planning to install an 'add-on' bidet to one of my toilet fixtures. The existing cut-off valve is a gate (?) multi-turn valve (chrome) which is connected to a 1/2" copper male adapter. (the house plumbing is Copper). While I am adding the bidet, I want to replace the 34yr old gate valve with a 1/4 turn ball valve. There is a stainless steel ball valve available. My question: any issues connecting stainless steel to copper? Or should I use a chrome ball valve (assuming I can find one). Home Depot/Lowes didn't have either a 1/2x1/2 ball valve or a 3/8x3/8 one. (all they had was compression).I don't think using a threaded sch40 ball valve would look very good although it would probably be 1/2 the cost. Should I be concerned about using dissimilar metals (corrosion on the copper?)

I will be installing a Tee at the base of the tank to provide a 3/8 NPT male connection to a 3/8" 1/4 turn ball valve to feed the bidet add-on (so that I can easily cut it off while my grandchildren are visiting to avoid a flooded bathroom from kids playing with the bidet).

The biggest hassle I foresee is draining the water out of pipes to be able to disconnect the existing 1/2" gate valve, because the house is 2 story and the toilet in question is on the 1st floor.

Any advice/tips on performing the job? I'm concerned about accidentally messing up the copper male adapter when taking of the 34yr old chrome valve.

  • 2
    Most residential supply shutoffs are made of brass with some plastic parts. Chrome is a finish or color. Stainless steel valves do exist but it's not common (I hesitate to say "never") to use one for a toilet shutoff. Stainless steel is also used as a name for a color or finish of plumbing parts. Are you sure you aren't looking at chrome and stainless finishes?
    – jay613
    Jun 24, 2023 at 0:27
  • If you cut off the threaded pipe end is there enough plain pipe left to shove on a compression or Sharkbite valve? There are all kinds of quarter-turn dual valves, but all the threaded inlet ones are multi-turn, which you rightly want to avoid. Can you add a picture of the valve location?
    – jay613
    Jun 24, 2023 at 0:37
  • I think there would be room for a shark bite, but I don't have a lot of faith in shark bite fittings over the long run. I will try to add a picture if I can figure out how to get it off the phone and onto the post.
    – peinal
    Jun 24, 2023 at 1:08
  • Are you ok with compression? My point was, you are concerned with accidentally damaging the threaded connector but I'm suggesting if you cut it off you can get what you want ... a nice one-piece dual shutoff valve. Unless you don't want compression either. :)
    – jay613
    Jun 24, 2023 at 1:37
  • Compression is OK.. certainly easier than sweating copper fittings.
    – peinal
    Jun 27, 2023 at 21:49

2 Answers 2


I like the stainless valve. The "chrome " are very likely chrome plated brass , which will work. Because brass and stainless are corrosion resistant in potable water, neither will corrode to cause a cathodic cell. There is a possibility that very old chrome plated valve is bronze which could be more corrosion resistant than brass. Likely only academic interest.

  • I'm fairly sure the valve is actual stainless steel, not just the finish. It's $15, instead of the $4-6 for 'normal' ones..
    – peinal
    Jun 24, 2023 at 1:04

Draining answer

After the main valve is closed, open a faucet closest to the main valve than open a faucet furthest away from main vale (second floor). That would create a drain path with drain vent allowing the water to drain. Meanwhile close the valves on the water heater since you do not want to drain it.

Galvanic answer

You are aware of it and do not have to be concerned, it will not impact your instal.

  • 2
    +1 for isolating the hot tank if it's on the ground floor. My tank is lower than any fixture so I never have to do that.
    – jay613
    Jun 24, 2023 at 0:42
  • My water main and water heater are in the basement. Will I be OK if I shut off the water main in the basement and then open the spigot next to it? Will that drain the water heater?
    – peinal
    Jun 24, 2023 at 1:01
  • @peinal you have a water tank inlet and outlet valves, close those
    – Traveler
    Jun 24, 2023 at 1:11

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