Let's talk grey water

Wastewater can be classified into two categories. Grey water is wastewater from non-toilet plumbing systems in your caravan or motorhome, such as your kitchen sink, ensuite hand basin, washing machine, and shower. Black water is that contaminated with faecal matter & urine - or grey water that has been stored longer than 12 hours.

Before getting into this topic in more detail, I would like to state

• I have a degree in Sustainability from the University of Tasmania

• I also have a Certificate III in Permaculture from TAFE NSW

• I lived on properties for 20 years that were not on town water or sewage, and therefore collected own water and managed own wastewater onsite
  

so... I am fairly well-educated in the topic of wastewater.

Grey water is one of those subjects that everyone disagrees on, so this Blog is my perspective based on my knowledge and life experience.

Why is grey water a problem?

Many people believe that its ok and even desirable to divert grey water onto the ground to water gardens and lawns. At the properties I lived at this is certainly something I did safely, however it’s not that simple in a caravan or motorhome for the following reasons.

Every family uses different products within their caravan/motorhome that end up in the grey water. These include, but are not limited to: soap, shampoo, conditioner, toothpaste, washing up detergent, washing detergent & softener, oils, and cleaning products. While some of these are considered relatively grey water safe (these are usually labelled “safe for septic tanks”), the majority contain chemicals harmful to our environment. Some even contain microplastics.

Grey water may also be considered polluted when contaminated with substances considered to be black water (e.g. if you have young kids who pee in the shower 😅).

Grey water, when stored, doesn’t stay "grey" for very long. Due to bacteria growth, grey water can turn to what is considered black water within 12 to 24 hours of being contained in a caravan or motorhome tank (especially in warm weather). Any food scraps, dead skin cells, hair etc also begin to decay. Hence why your grey water often smells a lot worse after storage.

Tips to improve your grey water

In order to make your grey water less offensive and better for the environment you can

• Choose septic-friendly products such as soaps, detergents and washing powders - these are usually labelled “safe for septic tanks”

• Avoid products with phosphates and chlorine

• Use vinegar and baking soda for cleaning rather than harmful chemicals

• Flush grey water hoses with water after use

• Clean grey water tanks regularly

• Filter out all solid matter and dispose of it with your regular rubbish, this includes hair, vegetable scraps, etc. Sink strainers are a great way to help manage this. Another is to put a stocking over the outlet of your grey water (which you need to change regularly).

• Do not tip oil down your kitchen sink, if its in a pan wipe with paper towel, if it’s a large amount in a saucepan or similar pour into a milk bottle or similar vessel and dispose with rubbish

• Don’t pee in your shower (urine is considered black water)

• Wipe plates, saucepans, eating utensils etc with paper towel before washing up

• When emptying grey water tanks, pour boiling water down your drains to eliminate grease build up. If done when emptying, this grease goes straight into the dump point or grey water disposal system.

Managing grey water in caravan parks

Many caravan parks will provide a grey water drain on or near your site where you can direct your grey water using an outlet hose. Some are purpose-built drains into which the grey water hose can be inserted, others may be an open drain.

Other caravan parks may not provide a grey water drain and instead may request you to direct grey water onto the grass or garden surrounding your site.

Caravan parks usually detail their grey water disposal policy in their terms & conditions (often attached to their site map they hand out on arrival). If it’s not clear, check with the caravan park reception.

Managing grey water at other camp sites

Many camp sites require caravans and motorhomes to be fully self-contained and this information should be provided upon booking and/or well signposted at the camp site. This means you must have the ability to store your grey water and take it with you when you leave. Some caravans and motorhomes are equipped with grey water tanks integrated into the plumbing and function by diverting the flow from the grey water outlet into the tank via a valve.

If your caravan or motorhome does not have an integrated grey water tank, some camp sites (but not all) will allow you to use an external or portable grey water tank.

It is extremely rare for primitive camp sites or free camps to provide any disposal systems for grey water. If there is no signage indicating you must be self-contained nor were you provided this information on booking, then it is usually ok to run your grey water onto the ground. In these cases, be very considerate of where you place your grey water hose outlet so that it doesn’t impact any other campers. You can also use a bucket and empty it well away from other campers.

Stored grey water

As discussed above, stored grey water doesn’t stay grey for long and when emptying your grey water tank it's best considered and handled as black water. That means storing it until you can access a dump point.

Effects of grey water on the environment

It is impossible for accommodation providers (such as caravan parks, national parks etc) to know what campers are putting in their grey water. At a simplistic level, grey water let into the environment untreated can result in

• The transmission of disease to both humans and animals where transmission can occur via direct contact, inhalation, contamination of water aquifers (e.g. bores), penetration through broken skin, or by insect vectors.

• Over time, soil may be harmed and its characteristics altered including saturation levels, salinity, permeability, pH, absorption capacity, chemical contamination.

• Plants can be harmed in the short term by high concentrations of salts and chemicals. While some plants may be able to cope with small applications or grey water, many plants, like Australian natives do not cope with the increased levels of phosphorus in grey water.

• If released into or near waterways, dams or lakes, grey water can fuel harmful algal blooms which cause mass ecosystem dysfunction by producing toxins, blocking sunlight and clogging fish gills. Fish reflect the quality of the water they live in, so polluted rivers = polluted fish.

• Frogs! While there is not a lot of research on whether grey water causes frogs harm… there is some evidence that toothpaste contamination causes frog eggs to hatch prematurely and some of its ingredients accumulate in fish (mainly triclosan, an antibacterial agent). We also know that the skin of frogs is very permeable and tadpoles use gills for breathing. Both these physiological characteristics make frogs and tadpoles very susceptible to any contaminants in their environment.

Questions or comments

Feel free to ask any questions or make comments below.

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