Engineering a community water distribution system

The first task would be to determine the present and future needs of the community.

The subdivision is well established and the water supply now will only be the 20 or so homes that have already been built and are occupied. The future needs are the existing homes as well as the lots that have not yet been improved. Each lot needs a service tap off the main. On our initial visit to the site I guessed that we would need about a 3" or 4" main to supply their requirements. I did not do any real calculations to determine what would actually be needed. That is a little out of my area of experience. There may also be issues to deal with regarding the production capacity of the existing well. There may be a need to install some pressurized storage to meet the peak demands. I don't think it's likely that the well will handle the volume needed directly. I recommended that the residents retain an engineer to design the system and then we could give them a proposal, based upon the requirements of that design, of the cost to install it.

Tell them they can purchase used S S Tanks from a Used Manufacturing Equipment Dealer and pump directly into it. They must be careful to have solid footers for the tank stand. They could also install some type of water treatment before or after the tank.

When first filling the tank the need to be careful on to over heat the pump or too pump the well dry.

If they are having problems will pressure after ther each house may need to install one way valves and a small pressure pump. They would then skip the need to install new water lines.

Just add a storage tank to the system for a start. Since it sounds like your community runs out of water from time to time a storage tank will provide volume for times of peak use. If the well does show a tendency to run dry add another well as far from the existing well as possible. If necessary add 2 wells, but the storage tank first so you can monitor consumption. Put the tank in the vicinity of the unsold lots and they can run their own feed rather than adding new demand to an old feed that may be undersized. Re-piping the entire community sounds terribly expensive.

Over the years as people come and go there needs to be an agreement as to who can and will be responsible for the maintenance of the main well pumping system. In years to come some will opt out for city water when it becomes available and others will not want the extra water bill. Some organize a neighborhood committees and have monthly meeting and dinners.

Most cities are happy to force you on to their sewer system but don't force you to use their water.

One community I know of has well water and there is a lot of complaining about who uses the most when it comes time to pay the $400.00 for a 1hp deep well pump and related labor cost to replace it. HINT -- Most Well Drilling Companies will NOT install the $400.00 pump you can buy at LOWE'S but require you buy their pumps for $1200.00 and they will replace up to a year free if anything goes wrong with it. Totally the cost for pump and labor will be $1500 to $2000.00. You know getting people to divide up that cost will be difficult even if they are all good friends. I small bank account could be set up to allow for some monthly dues for repairs to the system. Here they set a max for the account. Usually around $ 5000.00.

We use a tractor and boom pole to pull and replace the pumps around here. Just make sure if the tractor is leaking oils to have something to catch it on the ground.

A very crude starting point is that each person on average consumes 60 gallons per day.

Most systems supply around 20 PSIG at the house.

If there are 25 homes or an estimated 4 people in each than current needs are around 6,000 gallons per day.

That could get you the minimum size however most of the water use in a community like this is AM when everyone is taking showers and doing laundry and the evening when everyone is washing dishes.

You did not mention if this system provides fire protection or hydrents.

I hope that helps.

Do not use this estimate it is about 100 to 150 gpcd too low for a household. It is true that for the basic needs of a single individual they use about 60 to 75 gpcd, but there are other household uses besides shower, toilet and drinking water. I design small municipality and water district systems in California, most are primarily on wells in the san joaquin valley. The usage per capita day is typically ranging from 165 (very low) to 225 gpcd (high for municipal), upto 275 gpcd in some smaller rural communities with large lots (1 to 2 acre). The wealthier the property owners, the more water they use, also the larger the lots (typical lot size 4 per acre). With such a small community it is easy to figure the average per capita daily demand, just take the annual averaged daily demand, and divide by the number of persons total for the community.

Also, the system should supply at least 40 psig at the household when not under fire demand, and at least 20 psig at all service connections when there is a full fire demand.

You should retain a hydrogeologist and pump test the aquifer. Get some idea of the pumping capacity of the well. You may just need to upsize your well pump. However, a second well would provide some redundancy, should a well fail or water quality decline.

You should, and it may be required in your State since it is a industry standard, to install a storage tank with enough capacity to meet peak day demand plus a fire flow (tyically about 3000 gpm for 2 hours). Peak day demand is about 1.5 to 2.5 times your annual averaged daily demand.

The piping is sized to carry peak hour demand, which is about 4 to 6.5 times annual averaged daily demand for a very small community (these ratios drop as your community mixes usages and the population increases, but are good estimators to about 6000 people). Typically household connections are 1/2 inch to 1 inch size, and multi-family housing or larger properties may use 2 inch services.

As a rule i would suggest some form of metering be installed along the network (usually at service connections and at the wellheads). This will provide a means of monitoring system losses, as well as usages. This would resolve any internal disputes over water usage and may also identify any unaccounted losses indicative of a problem in the conveyance system.

You should retain a licensed civil engineer to take a look at your system, and do a quick study of projected demands and development through 2031 (water master planning), and prepare a system design report.

Go to the yellow pages and find a local professional engineer. Any public water system will require a licensed engineer to design it.

From my experiences with community water systems you're in for a lot of headaches. The best advice is to get a professional engineer in the area to make a study of what is required based on your needs and desires. The engineer will be the one to address the home owners and make them aware of the legal requirements and obligations they have. This way you won't be the one to bring "bad" news or requirements that some seem to think are unnecessary. Estimated usage can vary considerably by family as well as by season. When I was on such a system, the lots were 10 acres and most families had either a large lawn or a garden. My usage with a family of four and a few horses averaged 250-300 gallons/month in the winter and 500+ gallons/month in the summer. These figures are from a water meter that each family had on their in line. Another thing you will want to do is to get a good legal agreement drawn up for the water system. Again, the engineer can work with your attorney on making sure that all the proper points are included. Good luck with your project, I don't envy you!

Hmm, probably want to check that 500 gallon per month for 4 person, that is 4.167 gpcd (not counting the horses demands or irrigation). It is hard to believe your family survived on 4 gallons of water usage per day per person (while the lawn and horse died of thirst). This may be off by a factor of 100. Your meter may be oversized, and therefore doesn't read low flows accurately.

Thanks for catching my error. Does sound a little low! How about Changing that to gal./ day.