Is the water always up there?
How does the water get up there? I assume pumps but it all just doesn’t compute in my brain.
In: 1075
Ideally, yes, there’s always water. It provides water during high demand, like mornings, and gains water at night during low demand.
They also provide water pressure by nature of their height.
Yes, the water is pumped up there. Nothing really complicated going on. They use gravity to maintain water pressure in the system.
Water towers are used for two main features –
1. The act as water-pressure batteries. You pump the water once and fill the tower and now all that water is up high. Ideally it’s higher than any toilet or sink in the whole area. This way when you flush your toilet the water naturally goes down from the tower, across town in pipes, and up to your toilet tank all from the potential energy stored by pumping the water up. A big problem for domestic water is keeping it safe to drink, they solve this by keeping a constant pressure outwards from the tower to the faucet. This way and leak or break in a pipe would push water out rather than sucking bad stuff in.
2. EDIT SEE BELOW – They are self refilling. You pump the tower once and then leave it’s “water-in” pipe connected to the reservoir. As the tower drains it creates a natural suction that will suck water up the water-in pipe like you suck soda up a straw. So you don’t need constantly fill them 24/7.
EDIT – I was totally wrong about # 2 and I’ll own that. I’ll leave it there so people know I said wrong and learn from it. Thanks for everyone who helped explain why what I thought was impossible, I clearly misremembered something from school.
Yeah, you use electric pumps to get the water into the tower, and then the tower can provide water pressure throughout the system for free, courtesy of gravity.
Depending on the size and consumption of the water tower, it’s possible to only fill it at times when electricity demand is low and so the power cost will be lower.
But yes, the entire point is to leverage gravity as a free power source.
To get water to your faucet, it needs to be pushed through the pipes. We can just do that with pumps.
But when everyone takes a shower around the same time, we need *a lot* of pumps. Pumps that aren’t doing anything for the rest of the day when people aren’t all showering anymore.
So instead, we just put a bunch of water in a really tall thing. That way we can just use the sheer weight of all that water to push it through the pipes. We’ll still need pumps, just not so many. And when people are done showering, the pumps have free time to refill the tower.
For most municipal systems, they aren’t pumped up directly by pumps. There are pumps at the water plant that provide pressure to the system. That system water pressure is what determines the amount of water in the tank. The tank is just reserve water at static pressure so that when people start opening faucets there is reserve water that won’t immediately drop the pressure in the pipes. If that tank wasn’t there, whenever someone opened their faucet the immediate pressure would be very high, then drop to almost nothing because there wouldn’t be much excess water in the pipe and the pumps at the water plant would be cycling like crazy trying to maintain pressure.
Source: worked at municipal water plant.
The city have installed pumps that pushes water from the nearest source of clean water into the water pipes that run through the city. The problem is that these pumps are either on or off, there is no half way on. So when everyone wakes up and puts on the coffee maker the pumps is not able to pump enough water for everyone. And then when people sit down to enjoy the fresh cup of coffee the pumps are pushing lots of water into the pipes and the water have nowhere to go. Then again when everyone feels the effect of the coffee and takes a trip to the bathroom all the toilets is going to flush all the water out from the pipes again. That would be quite a sad city to live in.
The city have therefore installed water towers throughout the network. And what you see is what there is. It is just a long water pipe going up to a big tank, nothing more. The water in the tower will be pulled down by gravity into the water lines and out to all the houses. So when the pumps are unable to keep up with how much water people are using the additional water from the water tower will make up the difference. Then when people stop using water the pumps are still going full churn and the only way for the water in the water pipes to go is up the tower filling it from the bottom. This way the water pumps are going all day long even though people are using water at different rates.
So yes, the water tower is full of water, or sometimes almost down to the neck.
You pump water up there, and it sits there until it’s needed.
Just like electricity, water pressure always needs to meet demand. If a lot of people use water at once, without a water tower, you need exactly as much pressure from pumps being supplied as people are using. Over the course of a day, the amount of water used may only take 1 or 2 pumps, but if you look that the peak pressure being used, you might need 4. If you have 4 pumps, most of the time 2 of them will be sitting idle, and you need to very quickly turn them on or off to meet demand and you have 4x as many pumps to take care of.
With a water tower, it acts like a buffer. You could have 1 or 2 pumps running all the time just to get water up there, and while demand spikes, it just drains the tower, but when demand is low, it gets a chance to catch up and fill the tower back up. Also, if the power goes out, you still have limited access to water pressure with what was already pumped up into the tower.
Individual buildings may have water towers too (like in NYC) this is because the water pressure I the city pipes isn’t high enough to get above about the 10th floor of a building, so the building uses its own pump to get water up to the tower on the roof, and then that water gets supplied to the people above the 10th floor, and again gaining the benefits we mentioned about using water towers before.
If your city is on a hill, you may have multiple different water systems. One on top of the hill to supply people up there, and another lower on the hill because the water pressure would be too high if you took it down from the hill. (P=ρgh, pressure equals density * gravity * height)
Water is placed up high so it can push down on all the water in the pipes forcing it to flow out
Water guy here. Some of the Europen systems are adding variable speed pumps to their systems, to move water from the water treatment plant to the towers.
This means they can keep their towers at 90% all the time.
However, the most cost-effective pumps and controllers are the common on/off type that have one speed.
I’m sure you can imagine that huge pumps kicking on and off to maintain flow and pressure would cause pressure spikes and dips in the system.
In order to maintain an even steady pressure, you put a water tower between the pumps and the faucets.
When the water level gets down to 1/2, the pumps turn on, and at 95%, they turn off.
The sheer size of the water towers is because of their primary priority, which is fire fighting.
I found this out when discussing the failure of the softening system at the water plant.
Consumers were told that the water would not be softened for a week or so, and we were told that the towers must remain above 1/2 under all conditions because of fire-fighting needs during a power outage (no pumps available).
The water plant has a back-up generator, but they also have redundancies for emergencies.
1) The towers provide a fire-fighting reserve in case of a power outage.
2) The towers even-out the pressure and flow of water through the system, so its steady
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