The pump is not very noisy as made, but (as mentioned by others) the installation and the hard lines inside an RV amplify the minor pump sound!! Example: I am using one (same model as inside our trailer) to pump from a 200 gal tank to the trailer up on our property in NE WA. It is "plumbed" with 3/4" hose from tank and then to trailer. You can stand right next to it and all you hear is a hum from pump!! The trailer pump and lines have been modified and insulated from contact with cabinets and floor, and it is still not near as quiet as the outside pump!!! Better than when delivered, but the basic "rattle" is still there, but reduced to a more acceptable level!!!