Monday, 1 July 2013

The Source of the Problem

Water harvested from the wild has three problems which occur to a greater or lesser degree, depending on how and where it is harvested. Rainwater is pretty clean and clear, but picks up a few grollies when harvested as run-off from a roof. Underground springs, wells and aquifers are often pretty good, but a lot depends on where the water comes from and the type of rock or strata it passes through. Water pumped out of a ditch or land drain sounds like the worst possible option, so I decided to have a play with that first. I figured that if I could clean up that source as much as possible, then that would give me some valuable data to play with when it comes to implementing an off-grid water supply.

So what's in the ditch? Well, the ditch has a pretty good lining of clay which means it holds water quite well. There is a bit of loose mud and sediment in the bottom which is fine all the time the bed is undisturbed but this gets shaken up and makes the water pretty turbid when pumping. There is also plenty of 'livestock'...insect life, algae and frog and newt activity. Then there is all the stuff that I suspect is in there, but without some testing I can't be sure...nitrates, nitrites, pesticide and fertiliser residues and other nasties. Plus of course bacteria and pathogens.

All the problems I could encounter notwithstanding, most of the contents of the ditch - a good 95% I would say - is plain and simple, good old fashioned H2O. Which means I only need to get rid of perhaps 5% of the contents to leave me with reasonably clean water.

Would I drink from the ditch? No. Would I wash my hands in it? Definitely. Would I then eat an ice cream cone after washing my hands in it? Debatable.

I like to move it, move it

A song from the film Madegascar? Yes, and moving things around will be a major part of operations here on
the site.

Water, as previously mentioned, likes to flow downhill. Moving it uphill involves a little effort. There's 'bucket and chuck it', manual movement using mechanical means like Archimedian Screws or bucket elevators, or there are any number of ways of pumping water. Pumping seemed like a good way of doing things but the choice of pumps and methods of operation are numerous.

Looking at other resources available, I decided that I wanted to play with a low voltage system, having installed a 12v solar power/charging system down in the Toy Shed a year ago. If we're not using the system to top off vehicle batteries or charge the static battery for the inverter that runs the lights, then all that deliciously green and free energy is sat idle and going to waste. And as the sun has made an appearance this year, there's my energy source. So my power source is now either 12v DC, or inverted mains. Water and mains electricity do not make the best bed-fellows, and for temporary playing around, I'm not keen on spending a fortune on expensive gear so it's 12v DC and whatever I could find sculling around on ebay.

Enter the bilge pump! Two choices were obvious. Marine or RV/camping applications. Drilling down into the fine detail throw up two options - freshwater or wastewater. Figuring that I would be pumping from an unknown source, highly turbid and full of sediment and particulates (and the odd tadpole or pondskater here and there), I opted for a pump capable of contaminated water rather than potable water, so decided on a bilge pump for marine use.

The bilge pump is usually used with a float switch so that it can't run dry, and that is what I have done with my pump. Not likely to run dry in my applications, but a useful protection mechanism nonetheless.

The first thing I tried with the bilge pump was draining the surface water from the bottom of the Toy Shed. Although standing rainwater is pretty clean after settling, there is a lot of mud and sediment right at the bottom, so a method of mounting the pump and float switch that allowed some filtering of the sediment was needed. I had an old Curver plastic storage box sculling around, so I mounted the pump and float switch in the bottom, made up a set of flying leads that allowed me to connect to a battery, and drilled a row of 6mm holes around the base of the box, about 10mm up from the bottom. This allows water to drain in through the holes and let any sediment settle in the bottom. The pump only operates when there is 12-15mm of liquid, so this sedimentation doesn't affect the pump too much. The pump sits on a strainer base which also prevents large matter like grass or weed getting sucked up the pomp. The outflow of the pump is a 19mm bore hose outlet, so I have a length of 3/4" bore corrugated pond hose on the outlet. This will now drain the Toy Shed enough to leave just a couple of smallish puddles which soon dry up after a warm day or two.

The unit is also portable...I took it to a friends place to help with draining a pond in order to desludge it. I used the pump in the pond to suck out the water which I pumped into an old feed bag suspended in a water butt. The bag trappped all the weed, slime and sediment, allowing cleaner water to drain into the butt. The tap four inches above the bottom of the but also allowed for additional sedimentation, meaning that clean water could be returned to the pond after digging out the residual slime. Three evenings of pumping, digging, filtering and refilling left a much cleaner pond. After the job, the pump unit, butt and battery were dragged back up here in the back of Pudgy. Simples!

Water water everywhere, nor any drop to drink

One of the things we have in abundance here in West Wales is an almost unlimited supply of the wet stuff. It seems to fall out of the sky on a regular basis, although this summer has certainly been a lot dryer than the last couple of years.

The problem is, most of it is rainfall, a large chunk is runoff from the land surrounding us, and the majority of it ends up where we don't want it. We have some clay strata under the loose rock and soil, which means there is a lot of subsurface flow going in strange directions. Even if we've had a spell of no rain, this moving underground water is still, er, moving.

The Toy Shed sits in a little hollow at the bottom of the curtilage of the property, and in wet weather, pooling rainwater means welly-deep mire down at the lowest point. That's a third of the area with standing water.

I got to thinking about water, and how we could use it as a resource. Mains water is provided by Dwr Cymru (Welsh Water), and although they do a pretty good job of things - our water is lovely and soft - we have the problem of distance from mains, and capacity/bore of the supply pipe. If someone in the house flushes the loo or the washing machine starts to fill, there is a noticeable drop in pressure for anyone using a hose outside.

Consider then, the scenario of Mrs RT doing the laundry, me or Eco hosing down the machinery or topping up the pig's water trough and a horde of happy campers all wanting a shower or some water for drinking or cooking. Enough to go around, but you'll be getting a slow trickle rather than a forceful gush.

So our requirements are:

  • A domestic supply that doesn't suffer during peak camping periods
  • Guaranteed availability of plentiful water during peak demand times
  • Dealing with some of the 'unwanted' water we have sloshing about the place
Our domestic supply is paid-for potable mains water, so we would like to use that for the house as much as possible. Rainwater is great for washing down, watering plants and giving to the pigs and chooks, but under Water Regulations, counts as sewage for treatment purposes. It's pretty clean and clear coming out of the sky, but once it has run of a roof that birds have crapped on, may contain some pathogens and dirt.

We also have a spring that feeds a large pond below the house, so that is a potential source of supply.

One of the common methods of dealing with surface water or runoff is to use a system of land drains. These are ditches or trenches which are dug across the land in order to intercept surface water and carry it off to somewhere else. With a little careful thought, and adaption with time as you see how the drains operate at all states of the tide, these can go a long way towards water management. Add in a few underground drains or culverts to link these land drains under paths, tracks or thoroughfares, and you can move a lot of water a long way so long as you move it generally 'downhill'.

As shown in a previous post, we managed to install a culvert across the track to the ToyShed which has mitigated a major part of the problem with boggy rutted ground and permanent mud down in the tractor yard.

This culvert drains into a 'moat' around two sides of the Toy Shed, which not only acts as a land drain, but provides a 'buffer' for the Willow Plantation and a breeding ground for the local frog population. The culvert is still providing a flow of around 10 litres per minute into this moat even after very little rain in the last couple of months, so we are sure it is subterranean 'flow' we are intercepting.

So it is this 'moat' I have been using as my source water for a few water harvesting experiments.


Shame they don't make these anymore...

Having used a small motorcycle back in the late 80's to get to and from work, I haven't ridden a bike since then. This beast takes a little getting used to. Diesel engines are a whole different ball game from small petrol powered conveyances.