Backwash Valves - Troubleshooting

The backwash valve is one of the more troublesome parts of a pool system.  With proper maintenance, it should not be much of a problem, but it is important to be on the lookout for problem signs.

Valve is difficult to operate

A sticking valve is the earliest sign of problems.  This indicates that the valve is in need of lubrication.  It is time to disassemble the valve and inspect and lubricate the o-rings or gaskets.  If this is not done on a timely basis, then the o-rings or gaskets will wear badly leading to premature failure of these parts or the entire valve.  See the instructions under "annual maintenance" for servicing the valve.

Water is leaking at the valve

Sometimes you will see water leaking out where the valve shaft goes into the body of the valve.  This indicates a bad shaft o-ring on the valve.  This is more difficult to repair because it requires more disassembly than is normally required to service the valve.

Water is leaking to the backwash line in filter mode

Always be on the lookout for valves that have been added to the backwash line.  This creates a huge hazard and a liability risk.  If the pool operator tries to backwash without opening this valve, pressure will build up in the filter until the pump stalls out or something blows up.  This could severely injure or kill the pool operator.

Often people will add a valve like this instead of repairing the backwash valve.  This is a totally unacceptable method of repair.  The solution is to fix the valve right in the first place.

If water keeps trickling into the backwash line, even 15 minutes after the valve has been put on filter, then there is probably a bad gasket or o-ring on the valve.  NOTE:  After backwashing, it will take some time for the backwash line to clear of water, so some trickling is normal, but if it water keeps running out of the line 15 minutes after backwashing, then there is most likely a problem inside the valve. 

The easiest way to check out the problem further is to disassemble the valve and visually inspect the internals.  See the instructions under "annual maintenance" for servicing the valve.

Pool is cloudy

The backwash valve can sometimes malfunction in a way that causes the water to simply bypass the filter.

Notice how the o-ring is missing on the top wafer on the plunger.  While some filtration will actually take place, enough water can bypass the filter to cause the pool to stay cloudy.

One other indicator of this problem is seeing water return to the pool even in backwash mode as the diagram below demonstrates.  Notice that the backwash valve is in "backwash" mode with the handle pulled up. 

Normally, when the pool is in backwash mode, the pool returns should have no water returning through them, but if the top o-ring is missing, some water will be coming out of the pool returns, even in backwash mode.  A good pool operator will notice little things like this. 

Pool is losing water

The backwash valve can sometimes malfunction in a way that causes water to go out to the sewer line (as mentioned above).

While some of the water will still be filtered and return to the pool, a substantial amount of water will be lost to the sewer line, resulting in noticeable and sudden water loss in the pool.