What purpose does a water tower serve?

[Cluricaun]

You know, those big ball shaped towers with your town's name painted on them. What do those things do?

[hatesfreedom]

This is the best reason

http://www.roadsideamerica.com/attract/ ... _pyrka.jpg

[9004-70-0]

I always assumed they were artificial hills. We don't have any here--the reservoir is sitting atop a real hill, not far from the river the water is pumped from--but I have seen great numbers of them in the flatter states.

[BB Rodriguez]

"A water tower or elevated water tower is a large elevated water storage container constructed for the purpose of holding a water supply at a height sufficient to pressurize a water distribution system"

ETA: That, and of course where esle are local teenagers supposed to paint giant pot leaves?

[Giles]

As BB Rodriguez says, the main purpose is to provide a steady pressure in the water supply to the consumers, which won't fluctuate too much as demand goes up and down.

[What Exit?]

Basic but not detailed answer until an expert comes along is that Water Towers help with pressure in the city water supply. In some cases you pump the water up at night when electricity is cheaper and then let gravity provide the daytime pressure. In other cases it just helps keep pressure constant to prevent issues with too much or too little pressure. All water towers can also act as a reserve of water during peak usage.


ETA: Simul posting, we're quick.

[McNutty]

Note the distinction between "to provide water pressure" and "to provide a water pressure buffer." The city obviously already has a method to provide the water pressure, or they wouldn't be able to pump it up into the tower. But if they just hooked that water pressure directly to thousands of houses and all those houses turned on their taps at once, the pump at the source wouldn't be able to increase its rate enough to provide all those people with water pressure. So instead they use that pressure from the source to pump lots of water up into the tower, and if all the houses turn their taps on at once, the level in the tower starts dropping, but still provides (roughly) the same pressure the whole time. The tower capacity needs to be large enough so the tower doesn't completely drain during those peak usage times, and the rate the city is filling it needs to be high enough to get the reserve built up again in the off-peak times.

[hatesfreedom]

Apparantly your home insurance may be cheaper if your town has a water tower too. As they help greatly in providing water when you happen to blowing the towns load all at once (fires).

[Jules]

It does both, provide water storage and a water pressure buffer. If we didn't have one, we'd have to have a pressurized tank with an air bladder, to keep from having to run the pumps all the time. That's expensive, hard on the pumps, and hard on the system piping. If you're really coordinated, you can fill it at night when the power rates are cheaper, but mine just fills when it needs to, which is about every other day during the winter and twice a day during the summer when we water.

I run one of these systems, so ask away, but I'm outside working on installing water meters at the moment, so it may take me until evening to get back to you.

[Cluricaun]

Nope, that pretty much answers my question. So, just as an aside because I'd never do this, if you shot one with a high powered rifle, a bullet hole sized stream of water would shoot out the side?

[danceswithcats]

Apparantly your home insurance may be cheaper if your town has a water tower too. As they help greatly in providing water when you happen to blowing the towns load all at once (fires).

Kinda yes and kinda no. Your property insurance premiums are affected by the ISO rating of your municipality. Water supply is a component of that rating, but is only one of many, including career or volunteer fire department, age of FD equipment, hose components, other equipment, number of personnel and training, distance from station to your property, and so forth. Many municipalities have a split rating, such as 6/9, where 6 represents rating if within x distance of a hydrant, and 9 represents rating in a non hydranted area. The ISO scale ranks from 1-9, with one being the best.

[Jules]

Nope, that pretty much answers my question. So, just as an aside because I'd never do this, if you shot one with a high powered rifle, a bullet hole sized stream of water would shoot out the side?

Depends on how high-powered. It's pretty thick steel.

When I've overflowed mine, water shoots out the vents on the top and the side of the top. It's pretty spectacular, but you don't want to be parked underneath. Consider it a 2500 gpm rain shower.

[Santo Rugger]

FWIW, Bernoulli tells us that the increase in pressure is going to be equal to the height times the density of the fluid times the acceleration due to gravity (rho g h). So, a one meter of water is going to have a pressure of 9.8 kPa (kiloPascals) or one foot of water will give a psi of about .433 psi. So, neglecting frictional losses, a fifty foot tower will give us about 260 psi.

[danceswithcats]

FWIW, Bernoulli tells us that the increase in pressure is going to be equal to the height times the density of the fluid times the acceleration due to gravity (rho g h). So, a one meter of water is going to have a pressure of 9.8 kPa (kiloPascals) or one foot of water will give a psi of about .433 psi. So, neglecting frictional losses, a fifty foot tower will give us about 260 psi.

True. :wink: I wish I'd see 260 static at a hydrant. Were that the case, I wouldn't need to put the truck in pump gear. On a good day, I see 90 psi, but that doesn't guarantee the necessary flow for suppression. Pressure is only one aspect of the equation.

[Jules]

Er, are you sure on your math there? Because 50 feet times .433 (the same constant they give us) gives me about 21 psi at the base of the tower. My tower is 150 feet to the very top, and my system runs anywhere from 50 to 60 psi, depending on how full it is.

Yes, the firemen here often use the pumper trucks. I can see it on my pressure charts when they practice.

[parzival]

Er, are you sure on your math there? Because 50 feet times .433 (the same constant they give us) gives me about 21 psi at the base of the tower. My tower is 150 feet to the very top, and my system runs anywhere from 50 to 60 psi, depending on how full it is.

Yes, the firemen here often use the pumper trucks. I can see it on my pressure charts when they practice.

What's the 50 feet for? If it's 150 feet from base to top, that's roughly 60 psi, so you're getting the head you should expect.

[Jules]

Yes, I'm getting what I expect out of it; I was questioning Santo Rugger's numbers.

[Clayton_e]

Jules, I'm confused.. you have a water tower on your property? If so (way cool) but why? I grew up in a non piped area and just simply had a well drilled.. Besides some filter issues here and there had no problem and never ever nearly came near using the max flow.

[OtakuLoki]

I also am questioning Santo Rugger's numbers. From my Naval service training the rule of thumb that we'd been taught was that for every 100 feet of depth would translate to 100 PSIG on the outside of a submarine's hull. Granted, this is only static numbers, and only a rule of thumb, but it accords well with the numbers Jules is giving us.

[PrecambrianMollusc]

Santo has the correct gradient of 0.433 psi/ft, his calculation has gone squirly though.
For seawater 0.445/ft is a good estimate gradient so 100ft water depth should be 44.5 psi not 100 psi.

[Jules]

Jules, I'm confused.. you have a water tower on your property? If so (way cool) but why? I grew up in a non piped area and just simply had a well drilled.. Besides some filter issues here and there had no problem and never ever nearly came near using the max flow.

No, I run a small system professionally.

I've only got a well at home, with a bad pressure tank (that's being replaced today.) Really, you'd think a water operator could keep one stinkin' well going.

[Santo Rugger]

Santo has the correct gradient of 0.433 psi/ft, his calculation has gone squirly though.

Yeah, sorry about that, guys. You'll note the time of my post was just before quitting time. It was a math error, and running the numbers again a 50 foot tower would give us about 20 psi, and a 150 foot tower about 65 psi. This is assuming no losses, though, which isn't realistic. The real numbers would be a bit lower. Thanks for not letting the error stand, Domers!

[Badtz Maru]

Nope, that pretty much answers my question. So, just as an aside because I'd never do this, if you shot one with a high powered rifle, a bullet hole sized stream of water would shoot out the side?

I've always fantasized about blowing up a full water tower with high explosives. I think it would look awesome.

[Santo Rugger]

It'd look more impressive to see a BLEVE that contained a flammable gas.

[danceswithcats]

It'd look more impressive to see a BLEVE that contained a flammable gas.

Haven't seen a BLEVE other than in training films, but did see a house blow up from about 30' away. We had just arrived for an "assist the police-unknown type incident", and as I stopped the engine, the officer was going to call County to report nothing in evidence, but then we saw the Chief, followed by another police officer, and they were doing a credible imitation of Jesse Owens, running away from the row dwellings.

Little voice in my head said, "MOVE!" and the place lit off as I mashed the accelerator. It felt like the engine had been hit by another truck. Turns out the PD was chasing a guy, and he bailed from the still-moving vehicle in the alley behind the dwelling. The car hit the back wall and damaged the gas meter. The original officer took off in foot pursuit of the subject, and put in the call for FD, unaware of the extent of the problem.