Our cold RV water pressure at the kitchen sink is a trickle, both on city water and using our pump. The hot water pressure is fine. The shower and bathroom cold and hot water pressure are fine. What could be causing this problem? When we first purchased (new), the kitchen cold water pressure was tolerable but has steadily gotten worse over the years. Yes, we’ve cleaned out the faucet screen numerous times, which doesn’t account for the hot water flow being fine. —Chris, 2015 Nexus Viper 27
If the hot water flows out the faucet then it is not the screen as both hot and cold come to the faucet body and get mixed up through the head to the opening, as you suggested. There are not very many 2015 27-foot units coming up on the Google search to reference that type of floor plan and slides. But I did find a 27V, which should be close.
What I was looking for was where the kitchen sink was located and if it was in a slide room. I have found a few units that have gotten the plumbing pinched when they have faucets in a slide room. However, from what I can tell, yours is a fixed wall on the passenger side just back of the entrance door.
Check for RV water pressure obstructions
Since it is a low flow when connected to the city water pressure and the onboard pump, it has to be an obstruction in the cold water line somewhere between the faucet and the connection after the water pump. Your city water fill line bypasses the pump, but then the line coming from the pump connects to that line to supply water throughout the coach.
Typically these lines are ½-inch Cross-linked Polyethylene or PEX, which is a semi-rigid material but much more flexible than copper or the older PVC and CPVC used. The fittings can be either hard plastic that is crimped with a clamp ring or some type of compression fitting such as Flair-It™.
This is an illustration I have used several times showing the PEX and Flair-It used by Winnebago. Most manufacturers today are using a blue and red version of PEX to identify hot and cold. Here is an example of the colored PEX with clamp rings.
You should be able to open the cabinet door under the sink and tell which type of plumbing you have. I would start by tracing the cold water line from the faucet down into the cabinet and following it as far as you can. Verify it is not bent or kinked along the way. It’s not unusual to load cabinets and storage compartments with your stuff and shove something against the line and have it pinch. You should be able to follow it down into the lower compartments all the way to the pump.
If the hose isn’t kinked…
If you can’t find a kinked hose, then there must be an obstruction in a line or fitting. I would connect an air hose from a compressor set at 30 psi to the city water connection like you would do if you were winterizing. This will allow you to test pressure in the lines without blowing water all over the place. Open the faucet long enough to get all the air out of the line. Find the cold water line that connects to the faucet and if it is a compression fitting you can disconnect it and then check the airflow there. If it is good, the obstruction is in the faucet body, maybe at the seats in the valve. If not, you will need to keep tracing back and disconnecting fittings until you find it.
However, if you have clamp-on fittings like the photo above, it’s not as easy. You can cut the clamp; however, you will need a clamp tool to reconnect with a new clamp. Use a heat gun on low to heat the pipe and fitting to pull the hose off. Once again, you will need to follow the pipe and look at every connection until you find it.
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Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
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