1. Make sure the water heater is not leaking thru the drain plug or relief valve.
2. I took this from an rv repair site:
. Water Pump test:
•To test the water pump you will need a bucket of water and 2 short pieces of flexible water lines and a few clamps
•Fill the bucket with water
•Examine which line come into the water pump and which goes towards the motorhome – when you are sure mark them accordingly so you can reconnect them properly
•Disconnect your RV from your city water supply
•Turn off the water pump open all your faucets and let them drain, leave the faucets open
•Remove the pre marked water line from the pump inlet
•Attach one of the flexible hoses to the water pump inlet and tighten the clamp – make sure that the hose fits the water pump inlet, then take the other end of the hose you just attached to the pump and put it into a full bucket of water
•Remove the pre-marked water line that connects to the water pump outlet
•Attach the other flexible hose to the water pump outlet, tighten the clamp and point it at the ground
•Finally, have someone turn on the water pump and observe if water comes out:
* If the water pump makes a sound but no water comes out or if the steam of water is weak then the pump is defective or it could have a plugged up filter/screen. Depending on the pump model and manufacturer it my be possible to rebuild the pump.
* If water comes out but and the stream is strong, then it would seem that the water pump is okay and something else is causing the lack of water flow through the lines. At this point, we can’t suggest any further trouble shooting ideas, and suggest that you seek some professional assistance.