Water supply for a fire hydrant

February 11, 2013 7:28 AM

On my drive to work, I pass a power-line-trail. On the side of the road at the gate to the powerlines is a blue fire hydrant, and a little sign saying "non-potable water" by it. Why ?

I understand why the sign would be there (don't drink the water, don't fill up your RV's water tank with it, etc). What I don't understand is where the water is coming from ? There's no grey-water use (that I know of) in the area. The hydrant looks like a normal one -- so I don't think it's a borehole type (ie connected to groundwater, or the estuary about 500 yards away, so it would require a pump to pull water out). So is the sign bogus, or does this hydrant have a supply I'm not considering ?

(I've thought about hiking the powerline cut some time to see if there are additional blue hydrants, maybe the power company puts their own special water lines it along the cut ? )

Google street view of the hydrant

posted by k5.user to Grab Bag (14 answers total)

My first (uninformed, wildly speculative) guess is that it's using fittings or materials that are not appropriate for drinkable water - probably not containing lead solder, these days, but something like that.
posted by rmd1023 at 7:54 AM on February 11, 2013 [1 favorite]

I'd bet that there's a regulation stating it must be posted as such unless it's been tested to prove potability - perhaps because of the possibility of the fittings rmd1023 suggested, or because it's so far from any other test points.
posted by IAmBroom at 7:58 AM on February 11, 2013

It may be serviced from non-potable processed waste water (this is not the same thing as grey water) - this is apparantly pretty common for fire hydrants, and from random web searching it looks like some Virginia communities do this.
posted by muddgirl at 8:00 AM on February 11, 2013

This article states that blue hydrants contain water from a non-potable source. The coloring of hydrants reflects a lot of things...very interesting stuff.
posted by xingcat at 8:01 AM on February 11, 2013 [2 favorites]

Response by poster: (I should have added -- I haven't seen any other blue hydrants or "non-potable" signs in the area -- this one stands out as the only one I've noticed..)
posted by k5.user at 8:08 AM on February 11, 2013

Also, have you ever seen the water that comes out of a hydrant? It has been sitting in the pipes for some time and may be rusty. Around here they flush the hydrants periodically.
posted by jgreco at 8:08 AM on February 11, 2013

In a city, hydrants are usually fed from the general municipal supply, which is treated and potable. From the looks of where that hydrant is located, I'd say it's a dedicated fire line, which could be fed from nearly any sort of untreated source, including local ground waters or reservoirs. Thus, marking it as non-potable is probably required.
posted by Thorzdad at 8:18 AM on February 11, 2013 [2 favorites]

Best answer: It might be that the hydrant is on private property and is supplied by the power plant's own non-potable water source instead of the municipal water source, i.e. waste water of some form. Maybe water is needed for some part of their power-making process (know nothing about power plants specifically, so just speculating), and then they use it to supply their fire protection system as kind of a... secondary use for the untreated water.
posted by ohmy at 8:21 AM on February 11, 2013

As for the color...when I was a kid, the FD repainted all the hydrants in Indianapolis aqua blue. Turns out, the color stood-out like a sore thumb and made it much easier to locate a hydrant along the street from the cab of a speeding engine.
posted by Thorzdad at 8:48 AM on February 11, 2013

Best answer: Yeah my guess is the fittings as well. I used to work for a water hauling company, we filled people's potable water tanks (they normally live off of rainwater collection but if it doesn't rain...) and swimming pools mostly.

We had two kind of hoses, potable water hoses and fire hoses. To get water from our truck to a potable water tank we used the potable water hose, for swimming pools we used the fire hoses (much faster) BUT to get water into our truck we ALWAYS had to use the potable water hoses that way we were preventing contamination of our truck tank in general.

I guess what I'm trying to say is that it makes perfect sense to me that the water itself is potable but then it is running through something that isn't approved for drinking water transport, a pipe, a fitting, etc.
posted by magnetsphere at 9:05 AM on February 11, 2013

I can add that in municipal water systems, the amount of chlorine they use to treat the water is calculated by the size of the system, and at the end of the line, there may be much less chlorine in the water. Some of these systems may be designed to use the furthest reaches of the municipal system as fire service only, at the point where there is insufficient chlorine to adequately disinfect the line... But that's just a guess...
posted by joecacti at 9:42 AM on February 11, 2013

Best answer: Some cities near the Twin Cities in MN will use blue for water from the well side of the system. Generally it will not been treated yet so would probably be considered non-potable. It also has a lower pressure than a hydrant after the water treatment facility. They will use them if they have to but they will seek out a red hydrant first.
posted by Climber at 12:28 PM on February 11, 2013

Response by poster: Now that has me wondering how I could get the correct GIS layer for utilities and try to track down if the hydrant is getting "standard" water, some type of waste or grey water, "normal" water that hasn't been through the treatment plant yet or is a non-pressure pipe to the estuary, and try to work down from there.
posted by k5.user at 3:34 PM on February 11, 2013

Best answer: The flush (and somewhat weirdly washing) water at my workplace is pumped directly from one of the local lakes into the plumbing and is therefor posted as non-potable with dire warnings not to drink it. All our drinking water is delivered in water cooler jugs.

Zooming out on your link I'd bet that hydrant is being fed untreated from either the Walter Mill reservoir or the stream/river to the north.
posted by Mitheral at 7:52 PM on February 11, 2013