hook RO/DI to the sump

[wisesam]

Hi,
I am looking to add RO/DI filter and an auto top-off.
I kinda want to hook up the RO/DI directly to the sump with a float valve.
So when water drops, the float valve opens to allow filtered water into the sump.
But I have read some people advise against doing so because it may cause disaster if failed.
Has anyone done such similar setup?
Any advise is appreciated.