Clean water is more valuable than most of us realize

Clean water is more valuable than most of us realize. Clean water requires energy, so by conserving water, you're also conserving energy! You can help minimize its waste by installing a foot pedal to control your kitchen sink. We're going to install a couple of solenoid valves under your sink, and wire them up to a simple pedal. It's easier than you think, and you don't need any plumbing or electrical experience to do it. So, let's get started!
The heart of this project is a solenoid valve. Very simply, these are small bits of pipe that have a valve that will open or close when you apply electricity to them. I picked these up on eBay for about $15/ea (here's a search link to help).

Solenoid valves have a few important attributes:

the type of voltage required to activate them
whether they're open or closed when they're unpowered, and
the size or flow rate they will support.

For this project, we're going to want a pair of 12V DC, normally closed valves that will support about 3 GPM (gallons per minute). Typically, the larger diameter of the "pipe", the larger the flow rate. I went with 1/2" solenoid valves, and they're more than adequate for this project.
Some of this is going to depend on what size solenoid valves you go with, and what size fixtures you have under your sink. My fixtures were 3/8" (which I believe is standard), and my solenoid valve was 1/2" inch with male connectors on each end, so I needed adapters to go from 1/2" male to 3/8" male, and 1/2" male to 3/8" female. Your local home parts or plumbing store should carry these. Don't be afraid to ask for help, and if you already have your solenoid valves, bring one along to help avoid confusion. You will need one of each for each solenoid valve, so four adapters in total.

If you use a connector like the one in the first picture Bathtub Faucets Suppliersand your solenoid valve is plastic, you might want to try to find a 1/2" rubber washer, as going from brass to plastic can leak unless it's very tight. The adapter in the second picture has built-in rubber seals.
In order to activate the solenoids to let the water flow through them, we're going to need some sort of switch or pedal. Again, I went to eBay and found this one for about $9. If you have the talent, it wouldn't take much effort to make up your own pedal, but for this project I decided to go with a pre-made pedal.

You're also going to need some wire. I had some spare Faucet Ceramic Cartridges Manufacturersspeaker wire sitting around, and it was perfect for this project. I used about 12' of it, but that gave me plenty of slack to reposition the pedal.

Finally, you're going to need a power source. For this Instructable I used a pair of battery holders (one that holds 2 AA batteries, and one that holds a 9v battery (giving us 12V)). You can find these at Radio Shack or Fry's, or a similar store. You can also use a 12V DC adapter (a.k.a. "wall wart") if you'd prefer. The instructions will be the same, regardless, but if you use a 12V adapter, make sure you have a GFCI outlet installed.
As far as tools go, you will need either a wrench (5/8" or 16mm, or adjustable) or some pliers. A pair of wire strippers will be handy as well, but there's very little wiring to do, so you can probably strip the wires with a knife.

To make this Instructable as accessible as possible, I have done all of my electrical connections by twisting the wire and wrapping with electrical tape. If you have the means, I would recommend soldering the connections, but I wanted to show that it wasn't necessary.

You will also want a bowl to catch the small amount of water that will come out when we disconnect the hoses, and a towel handy just in case. Also, some sort of lighting for under the sink will probably make this much easier.
Your solenoid should have some kind of indicator as to the direction of flow (mine has a small arrow on the bottom). You're going to want to put the adapter that has a 3/8" female end on the "from" side of the arrow, and the 3/8" male end on the "to" side of the arrow (see first picture's annotations).

Next, grab half of your wire. Each of my pieces was about 6' in length in order to give me plenty of room to place the pedal where I wanted; you can adjust this for your project. Strip about 1" off of each end, and twist the wire up. Loop the wires through the contacts of the solenoid (see second picture). If you're using the solderless method, twist these up, and place a bit of electrical tape over them. If you're soldering them, then twist them up and solder them in place.

Finally, it will make installation easier if you wrap the wire around the valve (see third picture), just in order to keep it out of the way.