Dishwashers are a great convenience for most households, saving you hours every week of washing dishes by hand. Despite their convenience, they can be expensive to install. If you want to save on the labor costs, you can install one yourself. Before you can do that, though, you'll need to make sure that the existing plumbing is designed to support the added water-consuming appliance. If you don't already have a dishwasher in the house, you're going to need to add a three-way plumbing valve to the pipe so that you can connect the new dishwasher to the plumbing system.

How Do You Remove an Existing Two-Way Valve?

Close the water shut-off valve that supplies water to the kitchen. This will stop any water flow into the pipes so that you can disassemble the pipe to remove the valve without flooding your kitchen. Put a bucket under the pipes before you disconnect them, though, in case there's any residual water in the lines.

Use a faucet wrench to unscrew the compression nuts that connect the pipe to the faucet and the valve. The faucet wrench makes it easier to reach; it'll be a tight fit to work around the pipes otherwise.

Once you pull the riser pipe, cut the supply line using a tubing cutter. Place the cut as close as possible to the two-way valve so that you don't lose much of the length of the line. When you do this, you'll want to take your time and make sure that the cut is square. A clean cut is vital for proper fit, otherwise the new fitting won't be able to seal.

How Do You Connect the New Three-Way Valve?

Once you've removed the two-way valve, it's time to secure the three-way valve in place. Before you get started, make sure that you have both a new compression nut and a ferrule for the assembly. They should be supplied with the three-way valve when you buy it, but if they aren't you can buy them at any plumbing supply store.

Put a compression nut onto the exposed cut end of the existing pipe. Then, place a ferrule inside the nut. Put the valve in place on the pipe, making sure that you keep the ferrule secure against the threads of the nut. Then, slide the nut down over the ferrule to the valve and tighten it by hand until you can't turn it anymore.

Measure the distance from the dishwasher's main water supply valve to the new three-way valve that you've installed. You'll need to measure and cut pipe to run between the two. Additionally, you'll need to measure for the pipe that runs from the top of the three-way valve to your sink faucet. If your three-way valve hasn't altered the distance to the sink valve too much, you might still be able to use the existing riser pipe that you disconnected initially. Check it for a proper fit before you cut a new one.

After you measure and cut the line for the dishwasher, connect the lines to both the faucet and the dishwasher the same way as the initial valve connection. Use a compression nut and ferrule to ensure that the connections are secure. Once everything is tight, restore the water supply and then check every connection for signs of a leak. If anything is leaking, wrap the threads of that connection with plumber's tape.

With the information here, you can install a three-way valve under your sink with ease. This will allow you the water flow capacity to install a dishwasher and bring an end to your days of washing all of your dishes by hand. If you're not comfortable tackling the entire project on your own, a plumber like Lenny's Plumbing can help you ensure that it's done right.

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