Monday, January 4, 2016

Water in the context of Cape Town water restrictions (and our 2 simple greywater systems)

Cape Town instituted Level 2 water restrictions on 1 January. It's a very hot, dry summer. I wanted to talk about our water use in light of these restrictions. Not because we're perfect, but because we use so much less than we did in Observatory, despite watering many fairly large trees and having an extra family member.

I thought this graph on water use per day was a useful reference point. Essentially, what the graph tells us is that an average U.S. family of 5 uses about 89 kL per month. An average Indian family uses about 18kL per month. Apparently the average South Africa uses somewhere between 22KL and 37kL a month. As far as I can tell, these water calculations do not include the water used to produce commodities or food that we consume (that is, the water needed to produce a kg of beef consumed by a household, for example.) So for simplicity, I'm going to talk about domestic water use only.

Including watering large numbers of fruit trees, our water use has never exceeded 4kL/month on the farm. It is usually between 1 and 2 kL. Based on that, I'd say we use about 2kL of domestic water for our trees, and between 1 and 2kL/month for ourselves. In our old house, we used at least 7kL/month. As far as I can tell, the main reasons for the drop in usage is firstly, not having a flush toilet, and secondly, having very low water pressure in the house. But nevertheless I'm going to write through some other things that we do-- all of which conserve a lot of water, but which don't diminish our standard of living or happiness. And a lot of stuff is low-tech, experimental, and completely unprofessional (but all are safe from a sanitation/public health perspective).

Humanure toilet: I wrote about it briefly here. A flush toilet represents a household's biggest use of water. If I could become a weird eco-evangelist for something, it would probably be this. We are now using free waste organic oat straw (yeah... I know...) from a nearby neighbour's alpacas as our cover material. Previously I wondered if the cover material-- the carbon, essentially-- would be a hindrance to people. I now think that carbon is available in lots of places, and often goes to waste. Our compost pile does not smell, nor does it attract flies (all food waste goes to our worm bins).

Low-pressure water: We have low pressure because we bought a low-pressure geyser, so our hot water pressure is controlled by gravity, and the tank is not very high. So yeah, it was a mistake. But it works for us. It takes about 20 minutes to get a couple of inches of bath water, and we also use a lot less water when we shower and wash dishes. If your washing machine can handle it, one way to adjust water pressure is just to reduce the municipal pressure as it enters the property.

Elimination Communication with babies: We've done some amount of EC with all three kids. It wouldn't work for everyone, and it's quite dependent on the weather. A lot of our water is typically used for washing diapers and kids' clothes, and washing diapers takes more water than a regular load (you have to double rinse at minimum) So we save a lot of water when we avoid diaper-washing. This summer, with Hana, we only use diapers when we are out of the house and at night. Whereas typically we'd go through about 8-10 diapers a day (1 load), right now we usually only have to wash diapers every 3-4 days. EC works really well for our family as we have a pretty high tolerance for pee, our floors are wooden. Doing EC also meant our kids were completely out of diapers early, though that doesn't happen for everyone.

Greywater systems: We have two very simple greywater systems. They have their limitations, but they were what we could set up given our current skills, resources, and time-- and without buying anything. Important to note: there's nothing in any of our waste water that could poison waterways etc. In particular, we don't use any kind of detergent that contains phosphates.

Kitchen sink & Washing machine:

For the kitchen sink and washing machine, we have a meandering reed bed. We've checked, and the water comes out the other side looking clean (though we're not banking our health on that, either-- it goes into another garden bed, underground, and is never above ground so there is minimal risk of pathogens). That said, not everything comes out the other side. Quite a bit stays in the bed for a while, and the reeds are growing extraordinarily fast in there.

The design: Eug dug a trench that slanted downwards in a semi-circle. We then covered it with a piece of old black plastic we found on the property. Then we planted some reeds that were tolerant of being waterlogged. The water comes out of a 30mm pipe at the top of the semi circle, covered by some hay and an old tile. It moves slowly downwards, ending in a hugelbed.  The reeds are growing rapidly. The bark chips and straw between the reeds are remarkably quickly turning into a rich mud-- which means that I should soon dig out the mud between the reeds to replace with new straw. The hugelbed doesn't seem to benefit as much as it could from the water, so if we were to do it again, we'd continue the black plastic under the hugelbed also (a lot of it is probably draining away immediately after the plastic ends). On a day where we do multiple loads of laundry AND wash dishes, there's standing water in the greywater system, which isn't ideal (hence the need to dig out the mud-- which will be of great use in our annual garden anyway). It is covered with a lot of straw, which minimizes the possibility of bugs breeding and also makes the straw turn into soil pretty fast. I put more straw on every week or so. The neighbour's chickens scratch up the straw and-- I think-- eat bugs. So it doesn't have any smell or any bugs or larvae, but the water is also not necessarily being used as usefully as it might be. I'm hoping to cut back the reeds and use them as mulch now and then. We mainly just feel good knowing the water is not simply leaving our property. And we think the reeds are pretty.

Shower and bathroom sink water:
This would be clearer when the water is running, but there are little channels that go directly across the plastic to the trees.
As the water coming from our bathroom is relatively clean (only gentle soaps, no shampoo or body wash), there's no need for a reed bed and so we pipe it out the front of our house. I'd hoped that it could go all the way to irrigate our beginner food forest (about 20m away), but the logistics and potential expense seemed excessive. So we're trying a simple setup where we're giving the water to 6 moringa trees planted specifically for the system (to create a wind barrier in the front of our house, as well as for food and mulch). The water goes through our regular 30mm pipe, out about 6m away from our house where it enters an old gutter. The gutter has black plastic under it, and fills up moderately, then the water flows out of holes drilled at intervals so that each hole goes to one moringa tree. It's a basic system that gets around the issue of using traditional drip irrigation, which uses very thin pipes which may get clogged. It remains to be seen whether the moringa trees actually grow well in the system. The amount of water seems fairly reasonable, and given how sandy our soil is, drainage is not a major concern.

Rainwater collection:
So far we've been using municipal water for all of our irrigation, and this has been ok mainly because we don't have the water use associated with a toilet. In the long term, especially once the rain starts up in the autumn, we're hoping our rainwater tank will play a much more prominent role. We'd hoped it would be used for our household, but water pumps use too much electricity when they start so we've put that idea aside for now.

We use this diverter to collect the first water, so that the water in the actual tank is clean. Two gutters route the water into the Jojo tank (which you can see in the picture of kitchen greywater). There's a mint plant getting the first water that drips through the diverter. The 5000L tank has a tap, and the tap can be connected to a regular hose. We don't have much of an annual garden yet (mainly because the neighbour's chickens make attempts futile), but we're working on fencing so that we can start a pretty large annual garden close to our house, watered  solely with rainwater. We're thinking of using hugelbeds, and the idea is that even though it's only a 5000L tank, soaking beds over the rainy months will create a wet sponge effect that will gradually release water during the dry summer months. Again, we're not sure if this will work, but we're collecting as many free sources of mulch (straw, alpaca manure, leaves, horse manure) as we can, with the idea that the more organic matter, the more water holding capacity.

No comments: