Here's the hot ticket for injecting chlorine bleach into water via your hose.
This particular hose end fertilizer sprayer has both hose in and hose out connections
. Fill the jug with the appropriate amount of bleach, connect the hose to the input and a short hose between the output and your RV's hose connection, and you're good to go. Divert the city water connection to the fresh tank and turn on the water. Be sure to run the water pump to pickup and circulate the mixture through the pickup line and pump.
You can then refill the sprayer cup with about 1/2 cup of bleach, divert the city water from the fresh tank to the house and similarly sanitize your entire plumbing system.
The cup holds 32 oz. of bleach, so don't fill it full...at 1/4 cup bleach per 10 to 15 gallons, you may only need 2/3 to 1 cup (6 to 8 ounces) of bleach depending on your tank size. The hose end sprayer will pickup and disolve the bleach as the water goes through the sprayer.
I've used this method for years even with gravity feed. In fact, I install the fertilizer sprayer onto the hose bib (rather than the hose end), with a little extra bleach, and use the mixture to sanitize my potable water hoses connecting the household supply to the rig. Works great, and it's a no brainer.
I can't attest to the precise strength of the solution, but I know the cup is empty of bleach (no noticable smell) by the time I've filled my 30 gallon tank.
Jim & Renee
2020 Jayco Jay Feather X-213
previously 2014 Forest River/Rockwood HW 277
2006 Ram 1500 4WD Crew with Firestone Airbags
Every weekend boondocking in the National Forests or at Lake Vallecito