tds reading

[gwaco]

i borrowed a friends tds meter today just to see what the readings out of my r.o. unit are so let me know if you think good , bad or otherwise .
1. reading of r.o. water at room temp - 10 p.p.m.
2. reading of tap water at room temp - 220 p.p.m.
3. reading of publix grocery bottled water - 145 p.p.m.
so its pretty clear that the r.o. unit is working , but what is an agreed upon reading that is good ? 10 , 20 , 30 etc. p.p.m. ?
i know that 0 would be perfect and i wonder if adding a d.i. unit would drop it down to 0 , or is the ten reading good enough ?
the unit is made by hanna instruments and i don't know how good their reputation is . any thoughts ? gary

[ChrisPrusha]

I think a reading of 10 for an RO unit isn't bad. A DI will prolly drop it down zero, yes. Whether a reading of 10 is good or bad is a matter of opinion...but I always like to strive for zero myself.

I have a Hanna unit too...it's been working for me for years.

[gtoon159]

I replaced my pre-fiters when my TDS got that high. How long have you been running that unit?

If you are not changing your sediment and carbn filters every 6 months you will reduce the life of your membrane.

Adding a DI filter will only remove the Ionization from the water. A good thing to be sure but not required.