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Waste water

Blackwater is toilet wastewater containing feces, urine and flushwater from flush toilets along with anal cleansing water (if water is used for cleansing) or toilet paper. It is considered to be contaminated, and cannot be indiscriminately dumped.

Greywater is wastewater generated from washing food, clothes and dishware, as well as from bathing, but not from toilets. Especially if biodegradable cleaning products are used, this water is generally benign and can be safely disposed of into the ground (e.g. as irrigation water feeding plants), but not dumped into bodies of water (e.g. rivers, lakes), where the contained nutrients can become pollutants.


“The main question i have is in regards to grey water and black water. I think being offgrid poses issues for disposal because holding tanks have to be emptied eventually…”


For the tiny home, blackwater can be handled through:

  1. On-site processing, most cost-effectively done with a self-contained composting toilet, which quickly separates and evaporates the liquid/water component, and composts the solids.
  2. Disposal, either by direct connection to a sewage system, or by collection in a storage container and periodic dumping.

In small tiny home quantities, greywater can be run off into the ground. It shouldn't be stored for more than 24 hours, as pathogens can develop, turning it into blackwater.


  • Freezing winters are a big factor—frozen water can cause containers and plumbing to burst. Storage of both fresh and waste water, including whatever may be trapped in plumbing, has to take that into account. You'd want to make sure the house can be easily made freeze proof (containers emptied, plumbing drained) if left unattended long enough for anything to reach freezing temperature.
  • Have to take into account what the local regulations say, and how strictly you want to adhere to them.
  • Estimate your water usage for washing and bathing, how many liters/gallons of grey water will you have to deal with weekly? Necessary to properly consider options.
  • For greywater, you could have a dual system: a runoff pipe for a farm-type setting, and a sealed storage unit (like those wheeled RV containers) that can be periodically dumped, for a more urban/serviced area. Two options depending on location.
waste_water.txt · Last modified: 2017/01/16 04:27 (external edit)