City Supplied R/O Water - Tap

[customdusty]

My city just spend $18 million on a new city wide (for 6,500 customers) Reverse Osmosis plant for our drinking water, which has historically been very hard.

They said that our water quality is equal to or better than bottled water. They have only said that they cannot allow the water to be piped to our homes with no minerals because it will corrode our piping, so they add in a minute portion of minerals to counter act this. They are stating hardness levels will never exceed 100mg/L, which I don't understand anyways. I'm not sure if that is still high, or good, or if it is information that is unimportant for a reef tank.

My question: Can I use this water as is? If not, can I use some kind of a more basic tap filter to remove the remaining sparce impurities? Or, do I need to run my new R/O water through a R/O unit again?

[Icefire]

100mg/L = 100 ppm tds

ask what they add to the water

[Randy Holmes-Farley]

Copper from your own pipes can be the biggest problem (that's why they add stuff, and lead corrosion too), regardless of the quality of the water that the city sends out to you. Even with the pH raised by them, there can still be too much corrosion for a reef aquarium.

[AZDesertRat]

Almost always when a City builds and operates a RO treatment plant thye only treat a portion of the water with the RO and blend it with the existing water. This is often called side stream treatment. The reason for this is as Randy said RO water is agressive and will leach metals out of piping, fixtures and solders. By treating a portion of the water and blending they are able to meet EPA Drinking Water Standards and have lower operating costs than if they treated everything and then did remineralization and pH adjustments.
A hardness of 100 mg/L is equal to 6 grains per gallon of hardness which is not bad but does not equal having your own water softener and RO/DI unit. You need to get a water quality report showing what is in the water. I would imagine they are using an anti scaling agent for the RO plant and it may contain phosphates.

[moo0o]

wow lucky you. id love a tap tds that low!