Dishwasher shutoff valve doesn't totally stop water flow

I recently discovered that the supply line to my dishwasher was leaking, so I shut the water off under the sink, pulled the dishwasher and replaced the supply line.

Except what I discovered is that the valve under the sink didn’t totally stop the flow of water. I cranked it as tight as I dared, but there was still a slow flow, maybe an ounce a minute. For this repair I just put a big bowl under the dishwasher end of the supply line while I went to get a replacement, but it made me wonder if there are future cases I’m not thinking of where that wouldn’t work and I should get the valve replaced before it becomes a bigger problem.


You should get the valve replaced or repaired.

Is it a gate valve or ball valve?

There is a slight chance it is just some debris caught beneath the gate or hanging up the ball and it could be flushed out. More likely in a gate valve.
Sadly Ball Valves for domestic use had a tendency to go bad.

If you can access the valve I’ve had luck cleaning up the gates in the past and I’m not very good with plumbing.

Often you can rig a hose to do the flushing and avoid a major mess.

Assuming those are the only two kinds, it’s a gate valve. It has a football-shaped handle that turns multiple times to open/close. It’s a T with 2 valves on it, one that goes to the dishwasher, one to the sink’s hot water.

How do you rig a hose to do the flushing?

Since moving into my current house 5½ years ago, I have replace every sink faucet (4) and toilet (3). I have also replace all 11 valves because they all leaked. I am guessing all were original to the house that was built in 1993. All were gate type valves, I installed ball valves. I recently remodeled both upstairs bathrooms, none of the replacement valves leaked while installing new vanities and faucets.

It varies a lot for the hose. Depends on where the valve is and the closest open end after the valve. It is usually messy and annoying. I used a shop vacc hose to blast the water into a 13 gallon pail. I had the advantage of working in my basement.

Another time I shut off the water for the house, opened the valve up from the top (bonnet) and used a stiff brush to clean it out and then reassembled.

This. Gate valves are good at two things - 1) being either totally open or closed and 2) failing. Failure is even more likely when the valve is not exercised like the kind of valve that is only closed when something is leaking and you need to turn off the water in an emergency.

The valve is on a T with another valve about 2 inches away, so that should be doable. I’m assuming this is the original valve from when the house was built 17 years ago.

Sounds like I should replace with ball valves if I’m going to replace.

Next question would be, is it soldered, threaded or a pressure fitting?

The main shutoff to the house was a gate valve. It wouldn’t completely shut the water off, which made plumbing fixes a chore. One time, I tried to get it to close completely by twisting it as hard as I could - and broke the screw treads at the bottom! So, after shutting the water off at the meter, I disassembled the valve, and screwed it back onto the threads. For many years afterwards, I had to remember to always shut the water off at the meter (which was a ball (actually cylinder) valve).

The valve where it attaches to the house supply has a nut on it. Looking at pictures, that appears to be a compression fitting?

The outlets are 3/8" male threaded, onto which a 3/8" supply line like this attaches.

So far I have been unable to find a replacement on Home Depot’s website.

I’ll look around. Just so you know, the 3/8th outlets will have a pressure fitting ring and nut when in the box. Even if you are going to discard them and use a threaded supply line like in your picture.

Is it 1/2 inch coming off the main supply?

OOOhh. Thank you! Ok, I was looking for just the male threads, but the ring/nut was on all of them.

I think so. I’ll have to measure to be sure, but it’s slightly bigger than the outlets, and they are 3/8".


I spent about an hour in a Home Depot 10-15 years ago doing just that.