The so-called “green” harvesting of roof-shed rainwater with above-ground rain barrels or catch tanks reduces the watershed that currently overloads some of our municipal sewer and storm-water drainage systems. Still, could we do the same thing by installing underground cisterns similar to those used during the 1800’s and early 1900’s?
Description of the earlier cisterns
Many older homes and estates today still have the remnants of their early underground rainwater cisterns. These fairly large round, water-tight, root-free, 500-to-5000-gallon cisterns were made from brick, stone, rock, plaster, concrete, or combinations of these materials. They were each capped with an above-ground manhole-type of opening large enough to take a big bucket. This opening allowed the cistern to be periodically cleaned-out and repaired by the owner or by a third-party service.
The tin or zinc-plated guttering used on the house eaves then, which carried the rainwater down to the cisterns, were open and not covered. So, quite a bit of wind-blown tree leaves and seeds, and other debris could make their into the cisterns. For that reason, the suction end of the iron plumbing was located above the cistern floor, where the debris would eventually settle.
This relatively clean, soft, outside water supply was plumbed directly to the long-handle hand-pumps installed at the kitchen and bathroom sinks and the bathtub in the main house. It was also plumbed to the hand-pump in a small building behind the house that served as a summer kitchen and a place to wash laundry, to can garden produce, and to butcher chickens and hogs. This water supply remained relatively cool and unfrozen the year around. Generally, it was used for cooking, washing dishes, cleaning, canning, butchering, and bathing. But it could be drunk, too, after boiling it.
Modern cisterns operate much like the ones described above. However, instead of being built into the ground from scratch, they are buried prefabricated ones instead. That is, these cisterns could be prefabricated concrete receptacles, or they could be large prefabricated heavy-duty plastic tanks capped with fairly large screw-on tops, similar to the ones seen on certain lawn-treatment trucks.
Also, today’s aluminum, steel, plastic, or copper eave gutters will have porous or solid coverings. Thus, the amount of debris entering the cisterns from the rooftops will be minimal. Yet, the fine sand-like material shed by asphalt or composite shingles will need to be filtered out early during the harvesting process; else, 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 an electric one, its size and accessories will depend on how the harvested water is used.
More-than-likely, because most of us already have reliable purified municipal indoor drinking and bathing water supplies, this cistern water will be used for outdoor purposes, like, for the sprinkling of lawns and gardens, for filling fish ponds and small treated swimming pools, for watering trees and animals, and for washing vehicles, driveways, patios, decks, and houses. The following three advantages of the modern buried cistern system suggest this technology will work well today: 1) they are hidden from view and out-of-the-way by being underground, 2) they do not foster the production of algae or mosquitoes in the summer time, and 3) they help conserve the municipal storm-drainage systems and drinking water supplies.