So-called “green” rainwater harvesting from the roof with above-ground rain barrels or collection tanks reduces the watershed currently overloading some of our municipal sewer and stormwater drainage systems. Still, could we do the same by installing underground cisterns similar to those used during the 1800s and early 1900s?
Description of the previous tanks.
Today, many old houses and properties still retain the remains of their first underground rainwater cisterns. These fairly large, watertight, rootless, 500 to 5,000 gallon round cisterns were made from brick, stone, rock, plaster, concrete, or combinations of these materials. Each was covered with a manhole on the ground, large enough to hold a large bucket. This opening allowed the cleaning and periodic repair of the cistern by the owner or an external service.
The tin or zinc gutters that were then used in the eaves of the houses, which carried the rainwater to the cisterns, were open and not covered. Thus, quite a few windblown tree leaves and seeds, and other debris, could become cisterns. For that reason, the suction end of the iron pipe was located above the floor of the cistern, where the debris would eventually settle.
This relatively clean and gentle outdoor water supply was connected directly to the long-handled hand pumps installed in the kitchen and bathroom sinks and in the bathtub in the main house. It was also hooked up to the hand pump in a small building behind the house that served as a summer kitchen and a place for washing clothes, canning garden produce, and slaughtering chickens and pigs. This water supply remained relatively cold and thawed throughout the year. Generally, it was used for cooking, washing dishes, cleaning, canning, butchering, and bathing. But it can also be drunk after boiling it.
Modern cisterns work in much the same way as those described above. However, instead of being built into the ground from scratch, they are buried prefabricated. That is, these cisterns could be pre-cast concrete receptacles, or they could be large, high-strength pre-cast plastic tanks with fairly large screw caps, similar to those seen on certain lawn treatment trucks.
Additionally, today’s aluminum, steel, plastic, or copper eaves gutters will have porous or solid covers. Therefore, the amount of debris entering the cisterns from the rooftops will be minimal. However, fine sand-like material released by asphalt or composite shingles will need to be filtered early in the collection process; otherwise, it will eventually have to be removed from the buried cistern. Modern cistern plumbing will be heavy plastic. Of course, the pump itself will probably be electric, its size and accessories will depend on how the collected water is used.
Most likely, because most of us already have municipal supplies of purified and reliable drinking and bath water, this cistern water will be used for outdoor purposes such as spraying lawns and gardens, filling ponds. of fish and small pools treated. swimming pools, to water trees and animals, and to wash vehicles, driveways, patios, terraces and houses. The following three advantages of the modern buried tank system suggest that this technology will work well today: 1) they are hidden from view and out of the way when underground, 2) they do not encourage the production of algae or mosquitoes in the summer time, and 3) help to conserve municipal systems of storm drainage and drinking water supply.