Protect your pump with the Hansen Tank Leveller Valve.
Adding the leveller valve to your system means the tank only refills when it gets low.
By eliminating on/off cycling of your pump, it means your pump works less, requires less maintenance and provides a more reliable system. The Hansen Tank Leveller Valve combines well with rain water harvesting allowing the pump to only turn on when a minimum water level is reached. It also ensures that the pump can always supply enough water to prevent costly repairs caused by empty tanks.
The device enables setting minimum and maximum water levels. This prevents the constant turn on and off of the pump whenever minimal amounts of water are drawn off.
Can also be used with dirty water.
More info HERE (needs Adobe Acrobat)