1. Greywater Treatment

2. What is greywater? Not blackwater
Kitchen water is sometimes treated with blackwater due to its high solids content

3. What about black water?
Don’t make it black in the first place and save yourself the trouble of dealing with it.
And if you do, don’t mix it with the grey water, at least until after its treated.

4. What is in greywater that needs to be treated?
Mainly we are dealing with: fats, oils, detergents, soaps, food, hair.
Potentially may contain contaminants such as bacteria, protozoa, fungi and parasites.
In general it is pretty clean though, as long as you don’t store it.

5. What sort of volumes are we dealing with?
Varies hugely
From 220 litres per person per day
- Luxury homes with insinkerators,
high volume shower , bedays, etc
Down to 100 litres for households with compost toilets or re-used flush water
(numbers from A.R.C.)
The average per person is 180L (nth shore)

6. Average Household Water Use

7. Some more numbers to get a feel for where that water comes from
A toilet flush is usually either 11 L/5.5 L
or 6 L/3 L
The average is 5 flushes per person per day,
- 11L flush = 55litres x 4 people
= 220 L/day
= L / year

8. Washing machines Dishwasher Bath Shower
Average use between 100 & 200 Litres per wash.
Dishwasher
40L per load
Bath
150 – 200L
Shower
75L for every 5 minutes

9. Remember that water from rinsing her nappies will contain fecal matter

10. What are the benefits of on-site greywater treatment?

11. What are the drawbacks?

12. What are the onsite treatment options? Septic tanks are most common.

13. Standard disposal field

14. Benefits and drawbacks of septic tanks
Proven technology with a wide range of suppliers
Low or no power consumption
Inexpensive
Three-yearly pump-outs only
Drawbacks
Council may be resistant, especially on smaller sections and the system relies upon the soil for completion of treatment
Require sufficient land area and larger setbacks from ground and surface water
Dependent on the (sustained) treatment capacity of the soil
Nutrient loss off property

15. Aerated septic tanks

16. Benefits and drawbacks of aerated septic tanks
Wide range of off-the-peg systems
‘All-in-one’ packaged plants
Relatively economical to purchase
When operating well can produce a high quality effluent which makes disposal easier.
Well accepted by council
Drawbacks
Significant power consumption, expensive operation
Can be noisy
Maintenance can be costly (replacement pumps, etc)
Cope poorly with fluctuations in input (whether up or down) so less well suited to holiday homes, etc

17. Vermicomposting

18. Benefits and drawbacks of vermicompost system
Probably cope better than other systems with a garbage grinder and even some chemical use
Produce a reasonable quality effluent
Low (or no) power consumption
Can be quite compact units
Can be used with drip irrigation (some systems)
Drawbacks
Poor nutrient reduction (nitrogen/phosphorous) (may be OK or even a benefit if water is used appropriately in a low-sensitivity receiving environment)
Some councils accepting of well designed systems, others are less so.

19. Taking Multi tasking to the next level