Waterworks

Our water supply on the quinta comes from a stream that runs through it, plus a couple of small springs. When we first moved onto the land we collected buckets from the waterfall, then graduated to hose-piping our water direct from the stream for household use and irrigation.

But 2012 changed all that. We had a very dry summer following 2 years of failure of the winter rains. After diminishing to a mere trickle in February, the water in the stream stopped altogether in late August (the village above us used it all), only starting again when the rains did. I installed a 1,000-litre plastic drinking water tank for our household needs, fed mostly by spring water, leaving the stream for limited irrigation. The vegetable garden coped surprisingly well thanks to a lot of mulch, but we lost all our water-hungry plants like squashes. It really focused my attention on how vulnerable we are to drought. Since then I’ve been planning to build in as much water storage as practicable, and collect water both from the stream and from roof rainwater catchment.

Surveying the quinta for the water distribution network

This summer, along with all the other projects under way, we’ve been putting in some water tanks. Work has been progressing on a small rainwater catchment system for the smaller of the two buildings here, and also on two much larger tanks which will form the main hubs of our water distribution network, supporting both domestic use and irrigation.

My thinking on the subject of water and its storage has been enormously influenced by the work of Viktor Schauberger. Schauberger’s insights about water are profound and far reaching. He observed that when water is exposed to light and warmed by the sun, it loses its vitality and becomes sluggish. Exposed for long enough, it dies. He meant this quite literally – in his view water is a living thing, the lifeblood of the planet, rather than just a simple inorganic compound of hydrogen and oxygen. It’s at its most vigorous and vital when close to its maximum density, ie. at 4°C, and in darkness. It needs freedom to move, to flow, to meander, to be in the way that it is, not forced into straight lines or contained by straight walls at right angles to each other. Straight lines and angles prevent the formation of the natural vortices and circulation patterns that are essential to maintaining water in its optimum state of aeration. Consequently it stagnates, and like anything else that’s died, decomposes and becomes a breeding ground for bacteria, moulds and algae, requiring filtration and chemical treatment to make it ‘drinkable’ again.

The optimum shape of container for water storage is, according to Schauberger, an egg shape. We could do this in ferrocement, but it was going to comfortably exceed our limited budget, so we’ve got as close as we can by using stacked pre-cast concrete rings to form these two tanks, curving and shaping the bottom of the tank to remove the right angle between the walls and the base. Schauberger would doubtless not approve of using concrete, but it was the only economically viable material I could consider for tanks of this size.

The first to be built, on the eastern side of the quinta, will hold around 6,000 litres when it’s finished and supply the smaller building (the ‘wee house’) plus the irrigation tanks and terraces below. Up until now, there’s been no water supply this side of the quinta at all.

The 6,000-litre tank is fed from a main tank of roughly double that capacity built into the remains of what was once the uppermost holding tank for irrigation water right next to the stream. The pipeline between these two tanks will also supply the 1,000-litre tank for the cob bathroom, currently on a hosepipe feed direct from the stream. The main tank will also feed the larger building on the west side of the quinta.

This is how we built them …

Foundations for the 6,000-litre water tank – a level site dug out of bedrock and shuttered to hold the reinforced concrete base. The pipe in the centre is for drainage and cleaning

The concrete rings for the first water tank being unloaded

Bottom ring being lowered into place ready for the pour

Pouring the concrete base and setting in the first ring. Creating the egg-shaped profile at the bottom of the tank will happen at a much later stage

Once the concrete base had set, the remaining rings were ready to be stacked

The rings are bedded on cement mortar as they’re lowered into place

The last ring. The tank is 3m high

Finally, the lid or ‘biscuit’. This tank is in full sun for much of the year, so to keep the water in the best condition possible it will be half buried, surrounded by shade trees, and have perennial climbers like ivy grown all over it

The rings need to be jacketed in a coat of cement to make the tank watertight. In the absence of forms to rent for the purpose here, we made our own

Tank jacket formwork going into position

The jacket formwork gets ‘buttoned up’

Laying the base for the 12,000-litre tank was completed just in time!

Last ring being lowered onto the 12,000-litre water tank, bringing it up to the level of the track

The 12,000-litre water tank complete apart from ‘biscuit’ and jacket. This one is 4m high. It’s in a much shadier location than the 6,000-litre tank and will soon be surrounded by the cana (Arundo donax) that grows here, but it will still be covered with ivy to keep the water as cool as possible in summer

Although these tanks look enormous, the amount of water they hold is not a lot when considered in the context of irrigation requirements for a well-cultivated quinta. Together with our rainwater catchment capacity, both installed and planned, we’ll probably be storing no more than 30,000 litres in total (last year’s plans for a 33,000-litre ferrocement rainwater harvesting system have had to be changed due to budget constraints). The ponds, once completed, will keep another 10,000 litres or so on the quinta. But storing an entire summer’s irrigation requirements isn’t the intention. Once full, the tank system will be topped up daily for as long as the stream runs and if it does stop again in late August/early September, then we will hopefully have enough capacity to keep the vegetable garden on minimum maintenance watering until the winter rains come in.

Regardless, it will certainly be an improvement on what we had before.