hi, im just after drying out my van as i have once again flooded the van with overflowing water from my tank

this is really ping me off! its the 4th time in 2 years and im sick of it. i know use will say you should have checked it, but we all make mistakes. to the point of this post, do any of you's have float switches fitted to your tanks so to stop the overflowing of the tank and if so how exactly does it work and what materials will i need to do it? i fill from a large DI vessel straight into my tank as i have a very low TDS, its alot quicker than a RO, normally takes an hour to fill on a low pressure but i walk away and leave it and so has resulted in my tank overflowing a few times. any help would be greatly appreciated. Thanks