[jonny thompson]

Would it hurt my filters ro etc if every now and then I filled up my tank with hot water from my tap

[simon w]

Have you taken a TDS reading of both hot and cold?

Is your tank capable of holding hot water without seams giving out and splitting, allowing steam to escape etc?

[Spruce]

Would it hurt my filters ro etc if every now and then I filled up my tank with hot water from my tap

Why would you want to do that?

According to my Axeon HF5 membrane spec, the hottest temperature of water you can process is 45 degrees C.

If I look at my 4040 with an HF5 membrane, I'm using 1000 litres of water to process approx 450 litres of pure water. So 550 litres of waste water goes straight down the drain. So I would be wasting 550 litres of heated water; that's about 2 baths full.

Then of course you would need to know what the maximum water temperature the resin you use will tolerate.