Grey water – keeping gardens alive during water restrictions

Townsville is on Level 3 water restrictions as I write and is quite likely to be on Level 4  within a few months. If so, it’s very likely to stay on level 4 until we get our next Wet season.

Level 3 (sprinklers not to be used, handheld watering 6-7am and 6-7pm only, odds and evens applies to handheld watering) is tough enough on gardens – and gardeners – and Level 4 (no sprinklers or handheld watering allowed, watering cans/buckets only, odds and evens applies to watering cans/buckets) will be far worse. In these conditions, using grey water is one of the most significant options for helping our gardens to survive. Simple adaptations to our routines will be well worth the effort, even if more complex and expensive systems may not.

Grey Water vs Recycled Water

Both are ‘recycled’ in the sense of ‘re-used’ but the difference is that Grey water is used and then used again, without treatment, for a different purpose, whereas Recycled water has been used and treated before being returned to a distribution network. Grey (often) implies re-use at the household level, Recycled (usually) does not. Follow those two links to Wikipedia for more.

How grey?

1. Water from the washing machine – containing detergent, dirt from clothes and towels, etc.

2. Water from the shower, collected in a bucket or diverted from the waste pipe – detergent, dirt from our skin.

3. Water from the kitchen sink – detergent, grease and food scraps.

4. Water collected from air-con drains is not really ‘re-used’, but it is very clean and can be collected and used in the same ways as grey water.

Black water

Black water is ‘water’ from the toilet. It can’t be re-used without treatment so it can’t be called grey water but it needs to be mentioned.

The standard low-tech system (aka the good old Aussie dunny) involved a fixed seat above a bucket which was periodically emptied into a purpose-dug, and immediately refilled, pit; or a moveable outhouse (I’ve seen one on runners like a sledge) and, again, a sequence of pits. Either way, the ground in that area was particularly fertile afterwards but was left well alone until nature had had plenty of time to do the recycling.

Septic tank systems are the more modern stand-alone technology, widely used on rural properties and holiday houses. Some septic systems are designed to take grey water as well, but they are a distinct minority in my NQ experience as it’s an extra complication and it’s not really needed.

Composting toilets are even newer and probably most familiar from National Parks camping grounds.

What are we allowed to do?

The Townsville City Council website says:

You will need a council permit before installing either:

• a greywater diversion device, which diverts greywater from the bath, shower, hand basin and/or laundry to an irrigation hose. Untreated greywater cannot be stored

• a greywater treatment system, which collects the greywater and treats it to a high standard for reuse as garden irrigation.


You don’t need a permit for manual bucketing or connection of a flexible hose to a washing machine outlet.

Putting this together with my earlier suggestion that something simple may well be worthwhile but something complex may not:

  • The obvious initial set-up is one which sends washing machine water to the garden via an extension of the outlet hose (poly pipe works fine). Running it straight onto the lawn, garden or a tree is fine, although not on the veggie patch. (Two cautionary notes here: (1) remember to use biodegradable detergent and (2) if you’re washing nappies, switch the machine hose back to where it was, running into the sewer system, to avoid health problems.)
  • Stage 2 is to collect water from your air-con, putting a bucket underneath or extending the pipe with a flexible hose that you can direct on to different parts of your garden.
  • Stage 3 is to save shower water in a bucket and carry it out to your garden. Again, it’s okay to put straight on the lawn or garden.
  • Stage 4 might be to get a plumber (who should be able to help with council approval) to install a diversion on your bathroom outlet pipe, to collect all the water from both the shower and the hand-basin. If an underground irrigation system is required (and I have to admit I’m not sure whether it is or not), this might not be worth the money.
  • Stage 5 … getting serious here … would be a similar diversion on the kitchen sink and dishwasher. This water will have more nutrients; it may attract pests and will require more care. In fact, the TCC website says bluntly that, “Kitchen greywater is not suitable for reuse, as grease and oil can clog irrigation systems and build up on soil surfaces.”

Our best teachers

People who have always had limited water supplies and have had to be self-sufficient are our best teachers, and that means country people, especially out West. Visit a farmhouse and watch: all water used in the kitchen and bathroom drains onto the garden, often via a poly pipe which is moved as needed, and sometimes via some kind of basic greasetrap (there’s a fancy one here). If there’s a fixed open drain, it might run into a banana patch, since bananas are always thirsty. (A banana circle is a highly developed version of this idea.)

Other actions

If you get to somewhere around stage 3 on my list and the garden is still in drought, options other than more grey water may be better than stages 4 and 5. In no particular order, since circumstances vary so much:

  • If bores in your neighbourhood are good, put down your own.
  • Look into getting a rain-water tank. They are not as useful in a monsoonal climate as in places with a more even spread of rain through the year, but every little helps.
  • Check out TCC’s water saving tips here.
  • Mulch all your garden beds, to shade the soil and help retain the little water you have.
  • Re-plan your garden to have all the thirstiest plants together so that you’re not wasting water on plants which don’t need so much. Begin by grouping all your pot-plants according to water needs, with the thirsty ones nearest your water supply.
  • Reduce your lawn area, replacing some of it with other ground cover.
  • If we’re getting occasional little showers, as we are now, a big bucket under every downpipe around your house will let you put the water where it’s needed most. Just don’t let it sit there long enough to breed mozzies.

So what happens if I do all this and then it rains?

Keep it. Use it. It will reduce your water bill, reduce the strain on the city’s water supply, and come in handy next time the Wet fails – as it will.

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