The city has pulled a water line down the road so I can now stop getting water delivered if I can figure out how. The problem is that my house is about 700ft up a 200ft hill. The city pressure goes from 70psi to 0psi about 1/2- 2/3 of the way up the hill. So I need a pressure boost to get to hilltop. Assume I can get power, any booster suggestions?
It's way too soon to be picking products. First you need a strategy.
I see five delivery problems here.
- Getting enough pressure of water to climb your hill. Rule of thumb, you lose 1/2 PSI per vertical foot (a little high, but you'll need pressure for flow, too.)
- Getting enough volume of water up the hill for your instantaneous use. Pipe walls have a lot of drag, and you have a lot of pipe walls.
- Getting electricity down to the pump location. Perhaps ironically there's power right near the pump location, but not on your meter.
- Getting enough electricity to the pump location to satisfy your instantaneous use. Which could be quite a lot.
- Reliability of the pressure from the water company. OK it's 70 psi now and so you pick a location 100 feet up the hill, which 70 psi can serve. But what happens when all your neighbors shower at once and it plunges to 35 psi? Your pump goes dry since 35 psi can't push it up 100 feet! Yowch.
So there's no question in my mind that I'd put the booster pump as low as possible. That means both a water and electricity run for the full 700 feet, and that ain't chump change. So when reaching for Franklins, I first reach for a sharp pencil and the the old IBM "THINK" sign.
- if you size for instantaneous use - abandon the cistern - you have two problems. First, pipes and cords must be sized for worst-case surge, which means they are huge and expensive. (and tempting theft candy). Second, no power = no water.
- Since the cistern has worked for you, what if you keep it? Surge load is absorbed by the cistern, as it is now, and the pump and piping only need to refill the cistern (keep it topped up). It can do that at a very low rate with fairly small pump, pipe and wires. Still, no power, no water.
- Since you own land 700 feet wide and 200 feet high, any chance you own higher? Put your cistern up there (like this guy) and let that .433 PSI per vertical foot supply your water pressure. Now you're showering with no power! Also handy for firefighting, something to think about when sizing your cistern. Now your pump down low has to push even higher, but again only a trickle, just to top up the cistern.
Honestly, you have to price it all ways and decide which features you want.
So suppose you want a cistern system that can recover 240 gallons/day (seems like a lot.) That's 10 gallons per hour. 10 gallons weighs x8.3= 83 pounds. If you are lifting 200 ft, that is 83x200=16600 foot-pounds per hour of energy. 1 KWH is 2655220 ft-lbs., so this will take you .00625 kilowatt-hours per hour, or 6.25 watts. That has "solar" written all over it - derate 80% for solar availability (lifting 50 GPH 20% of the time) and you're still at 31 watts. Easy peasy.
If we wanted a surge/demand system that could supply 10 GPM, that's 600 GPH, 996000 ft-lbs per hour, 375 watt-hours per hour, assuming 39% pump efficiency, that's about 4 amps at 240V. 12 AWG wire ($479) can do that, but that assumes no friction losses in the pipe, which assumes fat pipe. You'd have to balance the cost of fat pipe vs the cost of thicker wire to pump up thinner pipe. That balance is above my skill level. Normally I'm all about conduit, but in this case I'd direct-bury the electrical cable so it isn't stolen.
Given that static head is 0.433 PSI per vertical foot of head, it's no surprise that 70 PSI won't make it up more than 161 vertical feet.
An additional consideration if you have 700 feet of pipe will be the dynamic head related to flow in that pipe, though if you are only feeding your existing cistern that flow can be quite small (but sustained for long times.) Dynamic head is basically pipe friction, and depends on the flow rate, the size of the pipe and the type of the pipe. If you are hoping to disconnect your cistern and run directly on city water piped to your fixtures you will have much more of a concern with dynamic head loss in the pipe than if you run the pipe to fill your cistern and it can putter away at half a gallon per minute for hours at a time, while your current system provides pressure to the household fixtures at normal flow rates.
Shopping questions are off topic, so "what booster pump to buy" is both off topic and not something you've actually got enough information to even try to answer.
- You'll have to pick a location for it, which will set the static head it will see. That may also affect power delivery options.
- You'll have to determine what role you want the city water connection to play - i.e. fill the cistern or stop using the cistern (the latter will require a more expensive pump and/or pipes.)
- Having chosen the role of the pump, you will either need to choose
pipes, or perhaps say to a pump supplier "these are the pipes I have, what can I do with them?"
- Pipe size and flow rate desired (or achievable) will determine the dynamic head and thus both the input and output conditions a proposed pump will see. Those will vary with the chosen pump, as will power requirements, so it becomes a matter of optimizing the variables you can change or are willing to change to solve the problem either as you desire or as you can afford to.
Many years ago I built a house on top of a hill but the only water on the property was 300+ feet below the home. What we did to controll the cost was to install several large cisterns the well pumped up to the first largest cistern then the next had a smaller and the last up at the house had a final one with a very small pump due to the total distance of close to 700 feet it was cheaper to have a service for the well at the bottom of the hill that fed the 2nd station. The home pressure pump was powered by a small 110v pump and pressure tank. The bottom cistern and middle had gas powered backup pumps along with a gas generator at the house to power the top. All this may sound crazy but it was way cheaper than trying to run all the pumps from the house and since the area was in the boonies and prone to power outages they needed the redundancy to get a loan. You may be able to do similar using smaller pumps to fill cisterns that way cheaper pumps & less power required .