I install small systems where people can't get a well but must supply water for public water users, which are defined as systems delivering water to more than 25 customers for more than 60 days. That includes a lot of summer youth camps and a few other places. I am often the last resort after they have spent $thousands on wells that don't meet their needs.Originally Posted by MaxBlack
I visit the sites, look at what they have, and engineer a system to use as much as possible of existing equipment while producing water that meets the EPA Surface Water Treatment Rule. That requirement is to filter and disinfect to remove or inactivate 99.9% of giardia lamblia cysts. A more recent requirement is to remove 99% of cryptosporidium oocysts. Anything that meets those requirements also kills viruses and bacteria.
Most of the systems treat 5000 to 20,000 gallons per day of water, but there is really no limit. The smallest system is less than 500 gallons per day where the water is pumped to a tank and the people carry away what they need in large buckets. That small one was declared a public water supply because they had more than 25 users carrying water from a dug well for more than 60 days per year.
The water is pumped from the lake or other water source, chlorinated and filtered through the cotton filters in a housing that I developed to put lots of surface area in an inexpensive housing, then into a contact tank that has enough contact time to kill or inactivate 97% of any giardia that get through the first filter. The tank is usually a 1500 to 3000 gallon polyethylene tank with baffles inside to prevent circulation directly from inlet to outlet.
Water is pumped from that tank through the Harmsco 1-micron-absolute filters (Cartridge PP-BB-20-1) into the distribution system. A chlorine residual is maintained throughout the system. http://www.harmsco.com/uploads/pdf/h...at_catalog.pdf
Operation of the system is automated so the operator has only to keep the chlorine tank supplied with sodium hypochlorite (usually generic household bleach) and make sure that the system is working.
The operators make daily measurements of water usage, chlorine residual, turbidity, pH, and temperature so they can verify that the system is meeting requirements. They are required to get a special "small systems operator" license, but operating the system depends more on diligence than on any special skills. Turbidity is never a problem because the cartridges are significantly better than is needed for the job.
This is a kind of hobby business in my retirement. I usually hear about a job when someone calls and says; "I can't get a well here and they told me to call you. Can you come up here and look at my place, and how fast can you put in a system?" My best (only) advertising is people who have my systems.