town water sources vary

I'm a firm believer in the importance of appropriate water for brewing. When I moved to my current town 2 years ago, I immediately educated myself on the water supply. The town has 3 wells, and pumps water from them into 1 main holding tank. Throughout the year, the mix from the 3 wells in that tank can vary significantly. They sometimes are pumping from all 3, other times they go a few weeks using just 1, maybe use 2 at a time etc. etc.

I've spoken to the folks in charge of the water in my town several times, and they don't seem very knowledgeable. They provide me with numbers, but are not able to elaborate on how they receive those numbers (average of several tests? 1 test is good enough?. Furthermore, after several emails and phone calls, once they finally do answer me, I can't help but get the impression that they're guesstimating, he says like that "yea you're looking at about 70 ppm for manganese" (even though I specifically ask him for magnesium).

So for the past year or so, I've been buying all distilled water and making from scratch. With 10 gallon batches, this is not only expensive but I often have to go to multiple stores to find enough for one batch.

I'm wondering if anyone else out there has a similar situation, or if anyone has any recommendations for what I can do. I dream of a day where I can use my own water right out of the hose, and dilute it with distilled to get where I want to be. I've considered collecting an array of samples over the course of a few months, and sending them in to Ward labs to compare for testing. I have little knowledge of municipal water supplies, but I have to imagine it's possible for all 3 of my wells to have very similar mineral amounts (all of the water comes from the same source, the Charles River Watershed). If I send them 3 or 4 samples collected over a long period of time, and they come back with very close amounts, maybe I can have confidence in the water then?

There are really only 2 approaches you can take here and you have hinted at both of them:
1. You can process an ensemble of samples to try to get a feel for the range of variation. If, as you mention, the 3 wells are similar and seasonal variations are limited you might be able to convince yourself that the variances are small enough that you do not need to be overly concerned with them. Sending off dozens of samples (and you'd need to do that many) will obviously enrichen Ward Labs. You would probably save money if you got kits for alkalinity and hardness and tested for those frequently with the occasional sample to Ward Labs as a bench mark.
2. Remove the variation in the supply by installing an RO unit. This too will cost you money but less than a dozen Ward Labs tests.

ajdelange said:

There are really only 2 approaches you can take here and you have hinted at both of them:
1. You can process an ensemble of samples to try to get a feel for the range of variation. If, as you mention, the 3 wells are similar and seasonal variations are limited you might be able to convince yourself that the variances are small enough that you do not need to be overly concerned with them. Sending off dozens of samples (and you'd need to do that many) will obviously enrichen Ward Labs. You would probably save money if you got kits for alkalinity and hardness and tested for those frequently with the occasional sample to Ward Labs as a bench mark.
2. Remove the variation in the supply by installing an RO unit. This too will cost you money but less than a dozen Ward Labs tests.

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Yea. you make a good point about the excessive quantity of Ward samples that would require. And even then I would never have extremely high confidence in my water.

The RO system idea is something Ive looked into, but only scratched the surface. I recall being turned off by the slow output rate. Would need to collect the brew water in the week (days?) leading up to the brewday. Unless I rigged up some kind of collection drum, spontaneous brewing would not be an option. But if that's the only downside, it's not so bad.

Groundwater wells are typically tapped into the same hydrogeologic unit when ever possible to reduce the variation in incoming water quality. The wells are spread apart to expand their intake capture zone to reduce the potential of drawing down the well field. The utility has an interest in keeping a consistent water quality in their pipes and the taste and performance consistent with their customers. Variation is more likely to create complaints.

It certainly is possible that the utility does not sit on a large aquifer and they have no choice but tap whatever water they find below. In that case, variation could occur. Has the utility indicated that the water quality from each of the wells is quite different? If its not too different, the relative amounts provided by each well may be inconsequential and the water quality might not vary too much.

RO water is a good alternative. But if the tap water is otherwise suitable and didn't actually vary its quality too much, then learning to work with your water could be much less expensive.

Martin - thanks for the reply. I plan to call my always informative water foreman tomorrow to see if he can confirm.

good news - the wells are all drilled into the same aquifer

Our municipality also draws from several wells, depending on the season and the needs of the water dept. When I was faced with this fact back in '06, coupled with the fact that the people I spoke with from the water dept. were very vague in their response to my questions, I decided to send off several samples to Ward Labs over the course of a couple of years to obtain an average of the water quality that I could expect.

What I discovered was that the water quality changed very little from sample to sample over that time. So now I just go with those figures and I've never had any problems when making mineral additions.