So-called “green” rainwater harvesting in roof sheds with rain barrels or above-ground collecting tanks reduces the watershed that currently overloads some of our municipal stormwater drainage and sewer systems. Still, could we do the same by installing underground cisterns similar to those used during the 19th and early 20th centuries?
Description of the above tanks
Many old houses and farms still have the remains of their first underground rainwater cisterns. These fairly large, round, airtight, rootless cisterns, 500 to 5,000 gallons, were made of brick, stone, rock, plaster, concrete, or combinations of these materials. Each was capped with an above-ground manhole large enough to hold a large bucket. This opening allowed the cistern to be periodically cleaned and repaired by the owner or by an external service.
The tin or zinc-plated gutters that were then used on the eaves of the houses, which lowered the rainwater to the cisterns, were open and not covered. Therefore, a large amount of windblown leaves and tree seeds and other debris could become the cisterns. For that reason, the suction end of the iron plumbing was located above the floor of the cistern, where debris would eventually settle.
This soft and relatively clean outside water supply was connected directly to long-handled hand pumps installed in the kitchen and bathroom sinks and in the bathtub in the main house. It was also connected to the hand pump in a small building behind the house that served as a summer kitchen and a place to wash clothes, pack garden produce, and slaughter chickens and pigs. This water supply remained relatively cool and thawed throughout the year. Generally, it was used for cooking, dishwashing, cleaning, canning, butchering, and bathing. But you could also drink it after boiling it.
modern cisterns
Modern cisterns work in much the same way as those described above. However, instead of being built on the ground from scratch, they are buried prefabricated. That is, these cisterns could be pre-cast concrete receptacles, or they could be large, heavy-duty, pre-cast plastic tanks capped with fairly large screw-on lids, similar to those seen on certain lawn treatment trucks.
Also, today’s aluminum, steel, plastic, or copper eave gutters will have porous or solid covers. Thus, the amount of debris entering the cisterns from the roofs will be minimal. However, fine sand-like material shed by asphalt or composite shingles will need to be filtered out early in the collection process; otherwise, it will eventually have to be removed from the buried cistern. The plumbing for the modern cistern will be heavy plastic pipe. Of course, the pump itself will probably be electric, its size and accessories will depend on how the collected water is used.
Chances are, since most of us already have municipal indoor bathing and drinking water supplies, this tanker water will be used for outdoor purposes, such as spraying lawns and gardens, filling ponds with fish and small baths treated. swimming pools, for watering trees and animals, and for washing vehicles, driveways, patios, decks, and houses. The following three advantages of the modern inground cistern system suggest that this technology will work well today: 1) they are hidden from view and out of the way by being underground, 2) they do not encourage algae or mosquito production during summer, and 3) help conserve municipal storm drainage systems and drinking water supplies.