My husband and I are building our home (by hand) and plan to use rainwater harvesting for our sole water source, and greywater for flushing toilets and irrigation.
As we have not yet begin to build our system (although we have bought the tanks), but will be soon, I need some advice in building our greywater system.
1. The source for our greywater will be diverting water from showers, bathtub, and laundry ONLY. NO sinks or dishwasher, therefore NO food particle contamination. Also, no diapers will be washed in the laundry. Will any of this assist with reducing or eliminating slimyness? If not, what would help?
2. Our greywater will be used for landscape irrigation, but more importantly, for flushing our toilets, per a recent change in Texas state law which now allows this for residential areas. We plan to use a 10 – 20 micron filter to help with cleanliness, due to flushing the toilets, as we would prefer the water in the toilets to be as clear as possible for aesthetic reasons. Will this be sufficient to address slimyness? Do we need to take additional steps?
3. Some of our greywater WILL be held for longer than 24 hours, as we need the ability to be able to consistently flush toilets. We plan to circulate the system via the filter/pump at least once a day. Will this be helpful? Do we need to modify our design?
4. What causes the slimyness? Fats? Algea?
All help is very appreciated as we have no backup.
Thank you,
Amanda
- Guest asked 9 years ago
- last edited 9 years ago
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Hi Amanda,
Answers to your questions inline below:
1. The source for our greywater will be diverting water from showers, bathtub, and laundry ONLY. NO sinks or dishwasher, therefore NO food particle contamination. Also, no diapers will be washed in the laundry. Will any of this assist with reducing or eliminating slimyness? If not, what would help?
The particles in greywater (soaps, dead skin, hair, lint, etc.) are food for microbes and will result in a slime, or biofilm, layer in your system. There is no way to eliminate it unless you have a more complex, expensive, system, like Nexus Ewater.
2. Our greywater will be used for landscape irrigation, but more importantly, for flushing our toilets, per a recent change in Texas state law which now allows this for residential areas. We plan to use a 10 – 20 micron filter to help with cleanliness, due to flushing the toilets, as we would prefer the water in the toilets to be as clear as possible for aesthetic reasons. Will this be sufficient to address slimyness? Do we need to take additional steps?
I strongly recommend you use your rainwater to flush toilets, NOT the greywater. It is much easier and lower cost to create a well functional rainwater system to flush toilets.
If you want to use greywater to flush, you’ll need disinfection as well as filtration. Even with filters and disinfection past greywater-to-toilet systems have caused increased corrosion of internal toilet tank parts, which creates wasteful leaks (imagine if a little slime builds up under the flapper, causing the toilet to leak, or the rubber corrodes).
I would recommend purchasing a manufactured system if you want to flush the toilet with greywater, though I don’t recommend using greywater for toilets at all if you have rainwater and irrigation need for the greywater.
3. Some of our greywater WILL be held for longer than 24 hours, as we need the ability to be able to consistently flush toilets. We plan to circulate the system via the filter/pump at least once a day. Will this be helpful? Do we need to modify our design?
Again, I think you should use rainwater for the toilets and greywater for irrigation.
4. What causes the slimyness? Fats? Algea?
Everything. Greywater is not clean! The particles in it feed microbes.
- Laura answered 9 years ago
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That’s a great project, Amanda — sounds like you’ve really planned it out well. I’ve worked with a few small greywater setups, and sliminess usually comes from organic buildup (soap residues, skin oils, and a bit of algae if light gets in). Using water only from showers and laundry definitely helps reduce it. The 10–20 micron filter should work fine for toilet flushing, but I’d also recommend keeping the system as shaded and sealed as possible to limit algae growth. Daily circulation through the filter is a smart move — that alone makes a big difference. Some folks also use a small dose of hydrogen peroxide occasionally to keep things clear, but it’s worth testing carefully if you go that route.
- john michael answered 1 month ago
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