Harvesting rainwater for your home means avoiding the microplastics which proliferate in both that from the utility and bottles.
We do not actually use water; it simply passes through our homes, bodies and gardens on its way to some dam and eventually back to the ocean via a river. A little of course evaporates.
More than enough lands on your roof in an average month in a summer rainfall area to supply all your needs for the whole year.
Like the free electrical energy landing on our rooves, the main problem is storage of that water; you have to be able to save enough for the long dry period.
More sensible is not to go off the municipal supply completely, but store enough for perhaps a couple months.
In 2016, for half a year, the KZN midlands, for example, had only 60mm of rain, but that is very exceptional.
Thankfully the summer rainfall pattern has returned and there is more than enough; if you can store it.
The average home might use about 20 kilolitres per month; storage of 40kl is the problem. That is enough for an average sized swimming pool.
In the end, some compromise is necessary, and we settled for 25kl; it is enough for the average dry winter, and has proved more than adequate in 2016.
A 25mm storm, on a 200 m2 roof would provide 0.025 x 200 = 5 kl. Five such rains would fill our reservoir. Daily usage would be less than one kilolitre. In practice, it is difficult collecting the water from the gutters on the far side of the house; you might aim to harvest half of that falling on your home.
Digging trenches and plumbing a series of standard sewage pipes to the reservoir proved very simple and inexpensive; one could add first-flush devices.
Your desire may be simply to go green; to use what the heavens provide instead of relying on your utility to supply all your needs. It may be that you are increasingly concerned that for various reasons that the authorities will in the future not be able to provide a continuous supply of unpolluted, potable water to your home.
High on the list of contaminants is asbestos from aging municipal-pipes; it causes a very serious bowel tumour called mesothelioma when drunk.
Whether it is E. Coli and other pathogens, or simply none at all, many South African towns have serious problems with both the provision and quality of the water reticulation.
Acid ground-water in mining areas and the products formed from the action of chlorine on organic matter are serious problems too.
And the auditor-general reports that the Department of Water and Sanitation is in crisis; it is not going to get better in the immediate future. If you want to be independent of these woes of the new South Africa then it is time to start planning. And, of course, the expense is offset by the increasing cost of municipal utilities.
Storage means use of either tanks like the Jo-Jo, or glass-fibre; the latter last forever, but cost a bit more. Both have the disadvantage of being unsightly and, above ground, any pathogens will flourish in the warm water.
We settled instead for a large underground reservoir, two metres deep and four in diameter, with a corrugated iron roof to keep the light out. A simple filter and pump will provide your home and garden with plentiful, high-pressure water.
The total cost was about R20,000. Payback time turned out to be six years, excluding all the health issues associated with polluted water, and the continuing frustration of empty taps.
Plastered correctly, the reservoir should not leak, but ours did; that meant fibre-glassing the whole, an extra cost of R15,000, but we now have zero losses, and in the summer the water level never drops more than a few centimetres.
We drink the water without reservation despite the hadedas that frequent our roof. And have not had the slightest problems; you could install a UV light or ozone it. More difficult are the leaves that trees deposit on the roof. Keeping the gutters clean is an on-going maintenance issue, but should be done anyway.
Going green is not without difficulties; harvesting and storing rainwater is no different. In the short term there is a considerable expense; in the longer period, having high quality, soft and clean water, free of chlorine in your home is without measure. Enjoying a generous fifteen-minute hot shower and knowing you are not detracting from the world in any way simply adds to the pleasure and relaxation.
Post chlorination is a very significant issue that needs to be faced for those concerned about their well-being.
To heck with water-saving and energy efficient showers. A solar generator easily drives the electric pump that supplies your home with the pristine stuff.
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