This float valve can be installed either vertically or horizontally. It accepts 1/4" icemaker / RO tubing.
It should be used with a top off reservoir, NOT hooked up directly in the sump to a RO/DI system!!!
If you are using this with an RO system: Install a float valve in the barrel / bucket / reservoir. When the water rises and lifts the float, the water stops flowing. The RO system pressurizes and turns itself off, and waste water stops flowing down the drain. However, the float valve uses a small rubber flap to hold the water pressure back, and the water can seep out a little bit at a time, causing the RO system to turn on briefly & waste water resumes. It's even possible for the unit to stay running because it isn't 100% pressurized.
What I recommend is using the float to keep your floors dry and to reduce the need for you to babysit the water production cycle. Check on it from time to time, and when you see that the vat is full, use a ball valve to close to the water line. This will stop any more water from flowing into the collection reservoir and shut off the RO system until you need to use it again.
This is how mine is set up, and it allows me to control when I want to make RO/DI water... It's best for the RO/DI's membrane to run it for a longer period instead of cycling it on and off multiple times per day. The float is hidden behind that condensation, just under the label on that container.
Accepts 1/4" ice maker / RO tubing. Installs vertically or horizontally.