Water Source

Only IF the Water Pump is ON AND you have the city Water fill tank valve in the wrong position. There should be no reason to have the Water Pump ON if on City Water. Doug

Agreed. Turn off the water pump. If you then have no water, you have settings wrong.

The city water enters the pipes AFTER the RV water pump. City water will not fill the water tank. City water will pressurize all the pipes downstream from the water pump, which is downstream from the water tank. Water will not flow backwards through the water pump to fill the tank either. There might be a valve lever to turn to send pressurized water from the city connection to the water tank. You know when the tank is full as water flows out the fill port of the water tank. Turn valve off at this point.
Some may not have a by-pass valve at all, so the only way to put water in the water tank is to physically run the hose into the water tank fill port.

diagram in words:
Water tank > Water pump > pipes > faucets/water heater/shower/toilet.

City connection > pipes > faucets/water heater/shower/toilet.

Water fill port (on outside of RV) > water tank > water pump > pipes > faucets/water heater/shower/toilet.

if included:
Bypass valve > water tank, AND Water tank > fill port > outside world.

ajriding wrote:
The city water enters the pipes AFTER the RV water pump. City water will not fill the water tank. City water will pressurize all the pipes downstream from the water pump, which is downstream from the water tank. Water will not flow backwards through the water pump to fill the tank either. There might be a valve lever to turn to send pressurized water from the city connection to the water tank. You know when the tank is full as water flows out the fill port of the water tank. Turn valve off at this point.
Some may not have a by-pass valve at all, so the only way to put water in the water tank is to physically run the hose into the water tank fill port.

diagram in words:
Water tank > Water pump > pipes > faucets/water heater/shower/toilet.

City connection > pipes > faucets/water heater/shower/toilet.

Water fill port (on outside of RV) > water tank > water pump > pipes > faucets/water heater/shower/toilet.

if included:
Bypass valve > water tank, AND Water tank > fill port > outside world.

Well, you CAN have a defective valve on the Water Pump that WILL backfill to the Fresh Tank. This type problem has manifested itself MORE in the past 5 years or so. Don't know if this is because they changed the design of the internal Water Pump check valve or this is just because there are millions more RV'ing now. This problem is usually on Shurflo brand water pumps. Doug

dougrainer wrote:
Only IF the Water Pump is ON AND you have the city Water fill tank valve in the wrong position. There should be no reason to have the Water Pump ON if on City Water. Doug

Duh... thanks.. never occurred to me to consider that... but it makes perfect sense, and so, another lesson learned.

Thanks again!

obiwancanoli wrote:

dougrainer wrote:
Only IF the Water Pump is ON AND you have the city Water fill tank valve in the wrong position. There should be no reason to have the Water Pump ON if on City Water. Doug

Duh... thanks.. never occurred to me to consider that... but it makes perfect sense, and so, another lesson learned.

Thanks again!

I should have elaborated further. EVEN if the fill valve is in the correct position(off), if you have the water pump ON and connected to City Water, you will still pull a little water out of the fresh tank when you use the fresh water. Not much, but over time will deplete the fresh tank. If you hear the pump run in this case you are pulling from the fresh tank also. Doug