Step 1
Obtain a spray nozzle and flexible hose. Dedicated kits are available from RV suppliers, but sink spray rinsers sold by home improvement stores will serve if a proprietary unit proves difficult to find.
Step 2
Turn off water pressure to the RV by disconnecting the shore connection hose. Check that the 12-volt water pump is switched off. These steps are not necessary if the water line to the toilet is fitted with an isolation tap. If it is, simply turn that tap clockwise as far as it will go.
Step 3
Remove the flexible water pipe from the back of the toilet by turning the nut on its end counterclockwise using as crescent wrench. Be careful if the pipe is attached directly to the water control component, properly called a vacuum breaker. If that's the case, hold the pipe steady with another pair of grips while breaking the seal of the nut. Vacuum breakers are not particularly strong, and they can break if you apply too much force to them.
Step 4
Attach one of the two in-line openings of the T-fitting to the back of the toilet or the now-vacant upstream inlet of the vacuum breaker. Attach the flexible water pipe to the opposite in-line opening. Attach the open end of the new sprayer nozzle’s hose to the right-angle opening of the T-fitting. Thread all of these components together by turning them clockwise until finger-tight, then give them a final one-eighth turn with a wrench. Support the vacuum breaker when applying pressure to any of the components.
Step 5
Reestablish water pressure, then visually inspect the connections for leaks. If water can be seen beading around any joint, simply give that joint an additional one-eighth turn clockwise until the beading stops.
Step 6
Install a retaining clip on a wall somewhere near the toilet if you don't want the head of the new sprayer simply lying on the floor. Such clips, sold by all home improvement stores, usually come with an attaching screw.