So I run my municipal tap water through a carbon filter, actually 2 of the same filters in-line...just so I can filter at a little higher flow rate. I have heard not to filter hot tap water through these, so I have been just using the cold water tap.

My question is this: in an effort to save time and energy heating up mash water, can I run 80F or 90F water through these filters? What is the upper limit to the temperature my water should be flowing through these filters? Also, is there any advantage/disadvantage to water flowing through at 40F compared to 90F?

I like to shave time off the brew day where I can, but not at the risk of reduced quality.

Cheers!

The Pur site says to not go above 100 degs. F.

One thing about warm water is you are pulling water from your hot water tank... The water doesnt taste nearly as good, so you may want to take that into consideration.

FWIW my tap (cold) water is 85ºF in the summer time and my whole house carbon filter from Home Depot works fine. I wouldn't want to go much higher than that though and certainly would not want to use the water from my water heater.

This is carbon fiber filter (not an activated carbon filter). It does nothing but remove particulate matter. The only limits on temperature would be those imposed by the housing and platic materials in the cartridge. Carbon fibre is good to temperatures well above boiling.

Someone did comment on what comes out of your water heater - nasty stuff. Yes, I know some small breweries use residential and commercial water heaters as HLT's but the water doesn't sit in them for days at elevated temperataure.

So if I run 90F water into my mash tun, I will be using something like 80% cold and 20% hot water from the water heater tank. Since the water from the hot water heater is going to be running through 2 filters, I don't really see a problem with sediment or off-flavor compounds getting through the filters?

What do you think...if it tastes good, it should be good to brew with right?

These filters will remove particulate matter but they will nor remove anything dissolved. Thus if there is an inordinate amount of, for example, copper dissolved in the hot water standing in the heater, that will come over undimininshed. The taste test is the ultimate but I have seen some health warnings about drinking hot water from the hot water heater. I suppose you could always run the hot water until you have flushed the tank and then draw your brewing water as soon as recovery is complete but it seems easier to just heat cold water and be on the safe side.

I only use my cold water source for brewing, but if you want to use water from the heater ... Flush the heater periodically, like every six months. As a matter of fact, this is a good idea even if you aren't using it for brewing. You don't have to drain the whole thing--just hook up a hose to the bottom outlet and run it for a minute or so.