Household Water – DIY Water Harvesting and Recycling

Introduction
The great thing about working to optimize the way you use and collect water for your home, is that you get to feel as though you are doing something practical to improve the environment without making sacrifices, but actually benefiting your household.

I bought a second-hand water tank, and mounted them all on a frame screwed through the metal roof, into the timber roof frame. The panels are still going strong 30 years later.

I bought a second-hand water tank, and mounted them all on a frame screwed through the metal roof, into the timber roof frame. The panels are still going strong 30 years later.

While we only need a few litres each of drinking water each day, cooking water should be potable quality, and laundry washing water should be free from impurities that would stain, such as iron deposits. The next quality down would be grey-water for vegetables and fruit trees, but only if it is applies via dripper, and not sprayed. Septic tank effluent is suitable for fruit trees, but must be applied via underground methods, such as gravel trenches, covered with soil. Ornamental plants and trees can use any standard of water in regard to cleanliness, however salt, nutrient, detergent and particulate content can be problems, as they can also be for the other uses.

While we only need a few litres each of drinking water each day, cooking water should be potable quality, and laundry washing water should be free from impurities that would stain, such as iron deposits. The next quality down would be grey-water for vegetables and fruit trees, but only if it is applies via dripper, and not sprayed. Septic tank effluent is suitable for fruit trees, but must be applied via underground methods, such as gravel trenches, covered with soil. Ornamental plants and trees can use any standard of water in regard to cleanliness, however salt, nutrient, detergent and particulate content can be problems, as they can also be for the other uses.

A acre block with a big ornamental garden of deciduous trees and shrubs in a temperate climate requires about 2,000 litres per week in the summer. You can calculate the water demand for a tree using the British Standard BS5837 1991, which gives a formula including the tree type and canopy diameter, the local evaporation rate. The watering frequency depends on the soil type and how much soil is available to each tree. Typically, a small tree takes 20 litres of water a day. Vegetables’ water demand depends very much on the variety and the weather. Partial shading is recommended for some varieties in the heat of summer.

Rainwater is easy to collect in plastic tanks, which are cheap and easy to handle and install, but take up space. Underground tanks are the opposite.

Getting Started
You can calculate the likely rain available using information from your local Meteorological Bureau. They will give you average rainfall each month. For example, in a location like Melbourne, it rains about 600mm each year, with rain pretty much uniform through the year. If your roof area is 200 square metres, and you want to catch it all, and assuming you want to store enough to water your garden for about a month, the tank volume needs to be about 1,000 x 200 x 0.6 / 12 = 10,000 litres. This gives you 10,000 / 30 = 333 litres per day. If you add this to your grey-water, originating from mains water supply, this gives you about 500 litres available for the garden. However, it is less if you use the tank water in the laundry.

Getting Started
You can calculate the likely rain available using information from your local Meteorological Bureau. They will give you average rainfall each month. For example, in a location like Melbourne, it rains about 600mm each year, with rain pretty much uniform through the year. If your roof area is 200 square metres, and you want to catch it all, and assuming you want to store enough to water your garden for about a month, the tank volume needs to be about 1,000 x 200 x 0.6 / 12 = 10,000 litres. This gives you 10,000 / 30 = 333 litres per day. If you add this to your grey-water, originating from mains water supply, this gives you about 500 litres available for the garden. However, it is less if you use the tank water in the laundry.

Becoming Proficient
It may take a while to get all the skills you need, and this is where the net can be useful. There are lots of government authority sites with heaps of information, as well as dedicated societies with lots of technical articles. Just have a go, and get started. The skills will build up as you go.

How Much Experience Is Needed?
You can do most of this sort of work without any experience, except for the electrics, that must be left to a qualified electrician, and any plumbing to do with sewage. Of course, working at heights, doing connections to gutters for example requires good safety practices.

Examples
With my grey-water system, I have a thriving orchard of about 14 trees, providing organic fruit over the summer and autumn. The underground water tank, just coming on line, collected 7,000 litres over one weekend of rain, from a roof area of 200 sq m.

The Best-Kept Secret About Home Water
By zoning your plants in the garden-planning phase, you can optimize your water use, by having the frequent- drinkers all grouped on the same pipe, and the bigger trees on a separate pipe. (I think you should also go for the biggest tank you can afford).

Staying On Top
To keep on top, you need to monitor your usage, to ensure you don’t just use more mains supply water as well as your recycled and harvested water. You need to keep the system clean: flush the drip lines and clean the roof gutters regularly. You also want to cycle the roof water with your recycled water, to reduce the build-up f salts in the soil.

Staying On Top
To keep on top, you need to monitor your usage, to ensure you don’t just use more mains supply water as well as your recycled and harvested water. You need to keep the system clean: flush the drip lines and clean the roof gutters regularly. You also want to cycle the roof water with your recycled water, to reduce the build-up f salts in the soil.

Blocked gutters are a problem, and regular maintenance is needed. Leaf-guard over the gutters is great, but quite expensive. In-line leaf-diverters are a good option. But they also need regular clean-outs.

Tank systems need mosquito-proof inlets and outlets.

ntroduction
The great thing about working to optimize the way you use and collect water for your home, is that you get to feel as though you are doing something practical to improve the environment without making sacrifices, but actually benefiting your household.

Blocked gutters are a problem, and regular maintenance is needed. Leaf-guard over the gutters is great, but quite expensive. In-line leaf-diverters are a good option. But they also need regular clean-outs.

Tank systems need mosquito-proof inlets and outlets.

If you are going to drink rainwater, your roof can’t be zinc-alume, as the aluminium is not good for you. You have to be aware of animal and bird droppings, as well as pollution fallout. A first-flush diverter will help a bit here.

Frank is a civil engineer practicing in the fields of geotechnical and structural engineering. He is a keen organic gardener, and has projects going to re-establish local-provenance flora and trees in local parks.

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Originally posted 2010-12-26 09:44:48.



2 Comments

  1. Arcosanti
    Posted July 7, 2011 at 3:39 am | Permalink

    In addition to the ways to collect water take a look at the AC condensation drip line. Here in Arizona I am getting about 6 gallons per day during the humid summer thunderstorm season.

  2. Posted July 7, 2011 at 8:08 am | Permalink

    Thanks for the tips.

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