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My graywater toilet flushing system


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Here is what I did to save a lot of water. I wanted to move away from flushing 200ml of urine away with 5>9 liters of pot able water. It started by me standing over a bucket while showering, then 2 buckets with a foot in every bucket, then me standing in a oval plastic wash basin. I then use the shower water to flush the toilet. I then got tired of carrying buckets around. I decided to dig a hole and plant a 200 liter blue plastic drum to catch the shower water (to prevent a possible collapse of the tank by the soil I filled the area around it with coarse sand mixed with dry cement, it became hard by drawing moisture from the surrounding soil). From the drum I use a small pump to transfer the water to a other container (68 L Rough Tote box) on a stand 1m above the toilet cistern. From there it is connected to the toilet cistern through a Stockman float valve (high flow low pressure valve). I use a normal float valve to control the level in the top box. I manually start the pump to fill the top box but I have a timer on the motor to stop it after 2 min or longer. If the need arrives I can still open the municipal water supply to the cistern if there is not enough showering vs using the toilet going on. 

What I found so far: never use washing machine water in this system as it starts to stink in 24hrs, normal untreated graywater takes about 5 days to become noticeable. I pop a chlorine pill in the underground tank (it last about 45 days) and if you flush the toilet there is a faint smell of chlorine which smells clean and fresh. I put a piece of shade cloth bag over the UG tank inlet to catch hair before it enters. There is a fine mesh filter between the UG tank and the top box, but it is of very little use after installing the shade cloth filter over the supply pipe. 

With a low flow shower rose we generate a little bit more shower water, than the toilet uses except if we get "non showering" visitors but this happened only once. If I see the UG drum have a bit too much residual water, around every 3 days, I change the pump outlet to the hosepipe and then water the garden. 

Previously I had to clean the UG and top box every 2 weeks due to funky smells but after not using washing machine water, the inlet filter and the chlorine pill everything is still smelling fresh and clean, the wife will inform me very fast if something starts to smell off.

We have nearly halved our municipal water consumption and now my garden gets more water than it ever did before. 

The pump can easily be moved to another blue 200L drum which collects the washing machine water but that gets pumped to the garden asap. 

Total diy cost was about R1000 (R400 second hand 0.37kw pump, R250 Stockman valve, R160 Rough Tote  68 liter box, R100 float valve for top box and then some pipes and gardena fittings and scrap wood and iron to build the stand). 

Enjoy, it can be done. 

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At our previous house I did something similar and tried to keep everything green.  I bought a 5000L 2nd hand JOJO tank and 12 flow-bins (1000L - also 2nd hand).  I stack 6 flow-bins on top of the other 6 and with (valves) taps I control the filling of these tanks with either rain or grey-water.    I very quickly realised that because of the quick "smell" of grey water I had to use only one flow-bin for the grey-water and the rest with rainwater.  

Filter system:  I got another flow bin and cut the top open and suspended (hang) 8 pots with "vleiland" plants (wetland filter) in it and install 2 old swimming pool sand-filter containers (one filled with wood chips and mulch and the other one with sand and stones) between this wetland cum sediment filter and the single flow-bin which I kept for the grey grey-water.   The wetland plants remove the heavy metals and other elements from the water which is mainly responsible for the bad smell.

Collection of the grey-water:  I dug a small pit, installed a plastic container in it and cut a square in the lid and glued aluminium gauze in the square area.  The outlets of our bathrooms, washing room and dishwasher then poured grey-water on top of this gauze into the container.  When full a float switch activated a pump, which pumped this newly donated fresh water up to the Wet-land/Sediment filter tank, which through gravitation slowly filter down to the greywater tank on ground level. 

Grey-water delivery to the toilets:   I used a small 12v DC solar driven diaphragm pump with pressure switch which connected to 3 toilet bowls through the original inlets.  I disconnected the municipality’s “drinking water” supply completely to prevent that our drinking water could get “infected” with this grey-water (although it was filtered in some way).  Whenever someone flushed a toilet the pressure dropped and the 12v pump got activated and filled the bowl until the filled bowl’s pressure stopped it again.  I also dropped a chlorine pill in the bowls of the toilets for disinfection and clean smell.


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  • 1 month later...

@Cassie such an awsum idea, I have been playing with the idea as well of having everything from the washing machine, baths and showers inc pool backwash to be drained into these pre-filters such as you have mentioned. 


Just the washing machine alone uses a ton of water that I could use again. However my water wouldn't be pumped back into the house. 

I would use the water to irrigate the garden as we have a big yard. 

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