With the D-D Flood Guardian, you can avoid unreliable float valves - simply mount the magnetic sensor on to your RO reservoir, then the solenoid valve inline between the prefilters and RO membrane.
When the water reaches the sensor the solenoid valve will be shutoff turning the water supply to the RO membrane off.
With normal shutoff systems for RO units, the water is topped up as soon as the level in the reservoir drops by a few millimetres. This prevents the RO unit from flushing properly, as it is constantly being turned on and off, leading to TDS creep.
With the use of a household timer, the Flood guardian can be set to turn on every 1-7 days as needed to fill the reservoir in one go flushing the RO unit properly and preventing this creep in TDS levels.
As the unit uses a magnetically mounted optical sensor, you do not need to drill holes in your RO reservoir or container. This also allows the sensor to be moved easily if required.