Camco 23303 Fresh Water Backflow Preventer, 1/2" Brass

A backflow preventer is one of those small brass fittings that does a big job quietly. The Camco 23303 sits on your fresh water line and makes sure water only moves in one direction, toward your water heater, and never gets pushed back into your potable supply. It's a check valve at heart. Water flows through in the right direction, and a stainless spring keeps it from coming back the other way. That's the whole trick, and it's exactly what you want protecting the clean side of your system.

Why does that matter? On an RV or a boat, your water heater and your fresh water tank share the same plumbing. Without a one-way valve in the right spot, heated or treated water can migrate back toward your freshwater lines, especially when pressures shift as the heater cycles or when you're running a bypass for winterizing. This little fitting stops that cold. It keeps the hot side and the fresh side honest with each other, which is exactly what you want when you're drinking from that tank.

Camco built the 23303 out of heavy-duty brass with a stainless steel spring inside. Brass is the right call here. It handles hot water, resists corrosion on a potable line, and threads cleanly without galling. The stainless spring is what keeps the check valve working season after season, since it's the one moving part and it lives in constant contact with water. Cheaper valves use materials that fatigue or corrode over time. This one is built to sit in the line and be forgotten, which is about the best thing you can say about a plumbing part you'll never think about again once it's installed.

It also complies with California and Vermont regulations for brass content, which is the low-lead standard for anything that touches drinking water. If you've ever tried to source plumbing parts and run into the lead-free requirement, you know it isn't optional in a lot of places anymore. The 23303 meets it, so you can put it on a potable water line without a second thought. The packaging is printed in English, French, and Spanish, which tells you it's the same part sold right across North America.

Installation is straightforward if you've done any threaded plumbing. One end is 1/2 inch male NPT, the other is 1/2 inch female NPT, so it threads inline on a standard half-inch fresh water connection. Wrap the male threads with a few turns of PTFE tape or a dab of potable-safe thread sealant, thread it in hand-tight, then snug it with a wrench. The one thing you can't skip is flow direction. A backflow preventer only works one way, so make sure the fitting points the direction water is meant to travel, toward the heater. Get it backwards and you'll block flow instead of protecting it.

Most folks install this right at the water heater inlet, which is where backflow does the most damage. It's also a smart addition when you set up a winterizing bypass, since you don't want antifreeze or drained water sneaking back into lines you've already cleared. And while Camco markets this one for RV water heaters, the same half-inch NPT freshwater plumbing shows up on plenty of boats with pressurized water systems and onboard heaters. If your fittings match, it works the same way out on the water.

It's an inexpensive part that prevents an expensive headache. One backflow preventer per box, brass and stainless, ready to thread into your system. If you're not sure whether your setup already has one, it's cheap insurance to add before your next trip. And if it's an older valve that's starting to weep or stick, swapping in a fresh one takes a few minutes. We're an authorized Camco dealer, so you're getting the genuine 23303 with the full manufacturer warranty behind it.