I've searched and haven't really seen this discussed much so here goes.

I'm getting ready to do some hydroponic stuff and have been researching tap water. Much to my only half-surprise, it is not recommended to use tap water. Partially because you have a harder time regulating your PPM and partially because you don't know what salts are in there. Also, I've read that lots of water supplies are moving to using chloramines that are not filtered out by activated charcoal (or distillation either). I'm also told these chloramines don't evaporate like chlorine does just by setting the water out for a few hours. Is there a concern with watering citrus with tap water? I'm trying to find out what exactly is in my tap water although I haven't been able to pinpoint the exact source of my water online. I think my water is the one with a fairly high level of Pb (and they have had beyond the legal limits a couple of times and were fined for it).

Also, has anyone been able to get the local water company to send a written copy of what is actually in the water? I'm going to try to do this but am having trouble finding the correct county department to call.

I have a small humidifier that I have near my citrus that I put about 1-2 quarts in a day and its been in use for about 6 months. I took it apart completely a few days ago and was shocked to see 1/4" slabs of brown salts collected (like sheets of ice really). I fill it with normal tap water but that was shocking to see that much salt collected in such a short time. I'd recommend no one actually drink this stuff that comes out of our faucets (except maybe well water). And I thought Seattle was known to have some of the best water in the country.

Is anyone else as concerned about our tap water?

Step number one should be have your water tested. There are several labs that will do water quality analysis and sometimes for free. From this point you know what problems (if any) you need to address.

Every lab I've seen costs like $10 to analyze each substance like NH3, Ca, Mg, Fe, etc. Looks like a several hundred dollar procedure. Any links to labs that do it more cheaply? Also, what have people on here paid to have the water analyzed? Has anyone gotten a report from the local gov't water treatment place?

thanks,
Todd

I had my water tested several years back, I don't remember the actual cost but it was under $100.00. My water come from a well. But if your water comes from a municipal water board, or an other governmental source, all you need to do is ask the supplier to give you their analysis report. At least here in Colorado the report is free for the asking. - Millet (633-)

Does the hardiness has anything to do with building salts in the soil much quicker?

I doubt the hardness of this water is contributing much to salt built-up. I have measured the total dissolved salts to be 28 ppm which I think is pretty low. However what is interesting is that I measure the pH to be about 7.0 but after filtering with a Brita filter the pH is about 5.0-5.5 with a tds of 14 (meaning its removing half the salts but increasing the pH substantially).

I'm trying to find out what department to call to get the water report but so far I haven't found the correct number - I'll try again tomorrow. I had read that water softeners increase the pH of the water but this was an eye opener to go from 7 to 5 is a hundred fold difference.

Look up your water system in the epa safe drinking water information system. Just google epa sdwis it'll be one of the first links. Your state may have a similar system. Texas has one that is just coming online. You should be able to find all the monitoring data there,
although it might be difficult to sift through. Be aware that sdwa only requires testing for chemicals of concern.

Thanks avinyard, but I've having trouble narrowing it down to exactly which water district serves me. It seems my zip code has multiple water districts and I can't narrow it down farther than that. When I was looking at what I think is the correct water district I noticed that it has several violations for excessive lead in the water. At this point I want to know exactly what is in the water and whether it is treated with chloramines so that I can figure out a better filter to buy.

Your water bill should tell you which district you're in.

Washington State Data is here:

http://www.doh.wa.gov/ehp/dw/sentry.htm

And this is the office of drinking water home page:

http://www.doh.wa.gov/ehp/dw/

They say you can request a report from your regional office, but expect a 4-6 week wait.

The big box stores sell mail in kits that might help you choose filters and whatnot for pretty cheap, but I wouldn't put too much faith in them.

This lab is friendlier to homeowners.

http://perrylaboratory.com/appraisal-services.shtml

Water Analyses
W-1: $77.00 Irrigation Suitability pH, electrical conductivity, calcium, magnesium, potassium, sodium, chloride, carbonate, bicarbonate, sulfate, nitrate, boron, SAR, iron, manganese, zinc, and copper

W-3: $36.00 Fertilizer Solution Analysis
pH, electrical conductivity, nitrate nitrogen, phosphorous, potassium

W-4 Nitrate $16.00
W-5 Molybdenum $16.00
W-6 Silica $16.00
W-7 Fluoride $16.00
W-8 Aluminum $16.00

Hydroponic Fertilizer Solution Analysis
W-9: $95.00 pH, electrical conductivity, nitrate and ammonium nitrogen, phosphorous, potassium, calcium, magnesium, sodium, chloride, carbonate, bicarbonate, sulfate, boron, iron, manganese, zinc, copper. Includes target values for some crops.

I left a message with the county water laboratory about 5 days ago. . .

My tax dollars not so hard at work.

In Germany the quality of tap water is regulated by law and analysis can usually download from the homepages of the water supplier... and the most tap water differ only in certain threshold ranges a little

Lets be serious! 99% of the home citrus growers use tap water. You will not kill your plant with whats in the water. The lack of water or the excess of water will kill it faster.
Also people are supposed to drink tap water. And some do (don't forget their pets). They would feel faster the effects of the bad tap water than a plant.

If you let your tap water stay in a bottle over the night before you actually water your plants you will eliminate almost all the problems (chlorine especially).

Regarding the hydroponics: why don't you experiment on a small batch of plants?

You're right !

Is it true that if you leave tap water overnight its quality improves? I don't believe it, because the salt concentration would get higher, because some of the water would evaporate and none of the salts would, so that would make salt concentration in the water higher.
I guess chlorine could evaporate, if it would be the actual Cl2 molecules in the water, but there are only Cl- ions in the water, that form when NaCl dissociates (salt that we use for food) and those I do not think that evaporate.
And don't forget that chlorine is also an essential trace element for citrus.