We are planning to use rainwater throughout the house wherever possible, so utilising our greywater (wastewater from showers, bath, laundry and hand basins) means that the water captured from our rooftop goes further.
Generally, the permaculture approach to water is to capture it, slow it and disperse it through the designed system (in this case the house, garden, ponds and trees) to utilise it in as many different ways as possible or feasible.
Of course, the less obvious part of this equation begins with our daily habits and being mindful of the length of our showers and the way in which we use the water that we currently use. It is estimated that in Australia a family of four is likely to use an average of 150,000 litres a year (just under 40,000 gallons). This equates to about 100 litres a day ( 26 gallons ) per family member. At present we have three adults showering – and the boys share a bath.
For the renovated house we will primarily be using rainwater as our main water source so I am keen to make this resource go as far as possible on a daily basis. We are already conscious of what goes into our greywater and choose to use environmentally friendly soaps and detergents. These have been extensively trialed over the years in our house and garden and do not appear in any way to have affected our research team of compost worms. In fact, they have thrived in our garden. Using scheme water on the other hand has often times been detrimental to some of our plants, quite likely an indication of its affect on the soil microbes. Over the years I have observed enough first hand, to make a determined effort to only use rainwater or filtered greywater (originally rainwater) on our garden area.
After many years of home-made grey water systems and variations on systems I have settled on using a commercial system for the new house.
The reason for this is that water will need to be pumped to the middle of the top of the block where its use can be best utilised. I also wanted a system what would be largely automatic and take care of itself. This is planned to be the case for the larger part, though once the water reaches its maximum distance and is flushed into the filter bed, most of the work is then done by gravity to slow it and spread it through the garden design. The heart of the operation will be the pump that shifts the water from under the house up to the garden.
I have mused over the filtering design for years and made the odd drawings of ideas on the back of envelopes and in note pads. Finally I have settled on a design for the waters journey, but I am not ruling out further changes once the actual construction and setting up of the design begins. Greywater is not deemed ideal for using on edible plants. Particulary not directly onto leaves and not for extended periods of time given that chemicals in the water could then build up in the soil.
I hope to have addressed this situation by opting to plumb rainwater into the house, supplementing with scheme water only when absolutely necessary. Once this water leaves the house and is pumped back to the garden via the greywater system we are now effectively dealing with dirty rainwater. In an effort to be pre-emptive about any possibility of chemical, bacterial or mineral build up in our precious vege garden I have been working on ways that this greywater can then be filtered and cleaned before passing through to the vegetable garden and orchard.
I also want this process to require my input as little as possible. That is one of the main conditions I have on the design of the water. That I am not required to attend to it to the extent that I have in our current property whereby the container gardens require regular attention for watering. I also do not want to delve into water reservoir gardens. My main desire is to have natural principles drive the system with minimal input from me for the majority of the garden area.
The down side of this commercial system is that we lose out on kitchen sink and dishwasher water. This is a regulatory condition outlined in the Department of Health Code of Practice for the Reuse of Greywater in Western Australia (2010). Previously we have managed this ourselves with no major concerns!
The system I chose is an approved direct diversion system. Given we were having the house plumbing considerably altered I was keen to get this system in straight from the start. Given it is a raised house and there is fairly reasonsable access under the house it is easy enough to get all the network in place. At the present time the house is greywater ready in that the plumbing is connected into a main channel that will direct water into the greywater sump box once it is installed.
In a nutshell, all sources of approved greywater are chanelled via the plumbing under the house and into the sump box whereupon any water entering the system activates the pump which diverts the water up into the garden area. This keeps pumping until the water level drops in the sump box and the pump turns off. There are non-return valves in the pipe at either end so that water does not flow back into the sump from the pipe once the pump turns off. I was concerned that with the quantity of water likely to be in the pipe, that this would trigger the pump to activate again. The non-return valves solve this problem.
The system also regularly flushes its own filter with water that is dispersed into the sewer pipe – as is any possible overflow from the system if burdened too much.
Due to the header height of the waters journey and where the junction of the main water pipes meet, the system was slightly modified to make the inlet pipe a little higher.