When to change your RO membranes?

At what ppm tds do you change out your RO membranes?

Personally, once my RO hits 15 ppm tds I change it out. It’s cheaper to change my RO membrane out yearly than to change my DI multiple times per month during busy season. I get my membranes from a friend who own a large industrial water filtration supply company.

For the first 6 months I use RO only with no DI, getting 000-003 ppm tds. Once it goes higher I use DI to polish things off.

What’s your RO tds ppm threshold?

As long as the tds coming out of the RO only is 10% - 15% of what is going into it you are ok.
Your local tds must be very low…lucky you.