How to appropriate lab water filtration?

July 31, 2008 12:04 PM

Is this fancy lab water filtration system also suitable for home filtration?

At my university's surplus outlet they have what I have come to find out is a laboratory water filtration system. There was a sticker on it with the serial "CDOF01205," which appears to be a part number (google pdf. p.5 for the part) for a package that includes an ion exchange and other expensive things that sound unnecessary for home water filtration.

The unit itself seems like pretty much a housing to push water through four filter canisters (that look from memory like the active carbon canisters for home filtration). It seems to be a first-generation Milli-Q from Millipore.

Can I put different canisters in this thing and use it to filter my house water? What's the flow rate like? Is the flow rate gonna be enough for the whole house? Do I just need activated carbon filters or what canisters would I need to use?

posted by cmoj to home & garden (13 comments total)

Well a lot of lab filtration systems required an input of de-ionized water which tastes really bad. This even further purifies that water, so I'd imagine it would taste even worse. (These don't just remove bacteria and chemical contaminates but also salts which will throw off buffer compositions etc. Salts are important to tasty water.) I'll try some tonight and tell you about it.

Other than that, yeah the water is pretty much good to go as long as there's no contaminates in the tubing etc. (And none on the output that would have been exposed to whatever was in the lab.) The filters though, if they are still available are ridiculously expensive.

Most of these filters also require a known pressure for input, the one in my lab has a regulator just before the input to reduce the building's DI water pressure to the range Millipore requires. Output is ridiculously slow, like around 1L/min or so. Maybe a little faster.
posted by Science! at 12:17 PM on July 31, 2008 [1 favorite]

It looks to me like that system acts as a de-ionizer, as well as a carbon filter. It seems to me that there is no conclusive proof that deionized water is safe to drink. However, I would remove the mixed bed reactor from the system if I were using such a device to purify household water.
posted by muddgirl at 12:18 PM on July 31, 2008

I should say "no proof that DI water is NOT safe to drink".
posted by muddgirl at 12:19 PM on July 31, 2008

Oh, and that system would be really really old and the filters are likely used up many times over.
posted by Science! at 12:19 PM on July 31, 2008

Upon further review, you should read the conclusion of this paper very carefully: Health risks from drinking demineralized water
posted by muddgirl at 12:23 PM on July 31, 2008

Seconding what everyone above said about the purpose of lab filtration--you don't actually want water with all the ions removed.

I worked in a lab with the Millipore system you linked to--it did require DI inflow and its output was quite low. It required a delay for power up time to work. And it, like most of them that I'm familiar with, really requires professional servicing, including changing all the different cartridges and filters every few months, to keep it working.

I suppose you could try it with just whatever kind of cartridge, but I'm not sure what the point would be. I see you are in the US--unless you are drinking contaminated well water or something, your drinking water is probably fine. If it's not, a lab DDI system is not what you need.
posted by hydropsyche at 12:25 PM on July 31, 2008

These things don't have that great of a flow rate. I've used a very similar model, and it would take maybe 10 minutes to fill a 20 L carboy. So certainly not sufficient for a house supply line: you wouldn't be able to take a shower with this thing inline.

A system like this is typically equipped with filters containing reverse osmosis membranes: that's what delivers the deionized water. I image you could just buy a bunch of activated carbon cartridges to replace the RO cartridges, and it would work like a standard home filter to remove organic contaminants. It looks like this might be what you need; $334 for four of them. Here's the page describing all the replacement cartridges available for models like this one.
posted by mr_roboto at 12:26 PM on July 31, 2008

Interesting. I've only ever swallowed a mouthful of DI water and it was bad enough that it never even crossed my mind to drink it regularly.
posted by Science! at 12:27 PM on July 31, 2008

Have you tasted lab water? Like Science! said, overly-filtered or de-ionized water tastes very different from ordinary distilled bottled water. It's a little like licking a metal pole or sucking on loose change. While interesting, you should probably try some before you put any money into such a purifier.
posted by cowbellemoo at 12:30 PM on July 31, 2008

Well, that was quick. The flow rate is the deal breaker. Good MetaJob.

As I should have made more explicit, My intention wasn't to drink the "lab water" but to convert it to regular household-quality filtered water. My intent in filtering tap water, incidentally, is getting rid of chlorine and fluoride.
posted by cmoj at 12:34 PM on July 31, 2008

You are going to have to get into the more expensive systems to reduce fluoride. If you're really worried about fluoride and chlorine, you may want to focus on two lower cost solutions to filter water where you're getting the most physical exposure: your shower and your drinking water. Here is a place to start. An appropriate home system is the way to go with this.

If flavor is your main issue an ordinary home system like Brita or Pur will be sufficient. They will reduce chlorine but they won't reduce fluoride significantly. Before you invest in an expensive home system you might want to get your water tested, read up on the science regarding fluoride, and think about how much purification you really need.
posted by nanojath at 1:03 PM on July 31, 2008

For the kind of drinking uses you describe, look into water purifiers marketed to the expensive pet fish market...
posted by acro at 1:38 PM on July 31, 2008

Chlorine: pretty much any carbon filter will do.

As for fluoride - average concentration is in the order of 1ppm. I'm almost positive that no regular household filter is able to reduce that by a significant amount (say, of an order of magnitude).
Besides the really nasty stuff (organochlorinated compounds and heavy metals) which is usually closely monitored, ions are generally your friends.
posted by _dario at 5:24 PM on July 31, 2008