Then just replace the sensors leads with brand new wire as before. If they last four months as you stated then just replace every four months. Personally I would go with SS probes and see if they last.

Thank you

 

Every Washing-Machine ever made has a cheap, reliable, Air-Pressure-Switch for controlling the Fill-Level.

That's what I had in mind, however, they are sensitive for controlling water levels on the order of maybe 25 inches from small load to large load. To use a washing machine level sensor you would probably have to modify the spring to get the response you want. I still think a pressure gauge is the easiest way to go. No maintenance, no power. The ONLY thing I could think of would be a float switch at the top to shut off the pump - that is IF the tank is filled via a pump. If it's filled by a valve then you'd need an electric valve to shut the water flow off before the tank could overflow.

 

A six foot high tank (assuming a 5 foot radius) would hold 141 cubic feet of water.

Did you mean diameter? You said radius. That'd be a 10 foot diameter tank. 10' diameter x 6' depth = 471 cubic feet.
(10' ÷ 2)•Pi•R^2 = 78.5 sq. ft. That times 6' = 471 cu.ft. That'd be over 3500 gallons. In my house that's a winter month's supply of water for two people.

 

Did you mean diameter? You said radius. That'd be a 10 foot diameter tank. 10' diameter x 6' depth = 471 cubic feet.
(10' ÷ 2)•Pi•R^2 = 78.5 sq. ft. That times 6' = 471 cu.ft. That'd be over 3500 gallons. In my house that's a winter month's supply of water for two people.

The TS mentioned 6ft and 4000L closer to 5 ft in diameter if round

 

The TS mentioned 6ft and 4000L closer to 5 ft in diameter if round

Guess I overlooked that detail.

 

The Washing-Machine Water-Level-Switches measure the Water-Pressure at the end
of the Tube that is connected to them.
Simply using different length plastic or rubber Tubes will produce indications at various levels in the Tank.
A weight on the end of the Tube will keep it stretched-out-straight, then some type of
Clamp at the top of the Tubes to hold them in place will set the Level, and produce repeatable results.
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