Reed bed construction

As we are now in the middle of the winter, it was time for us to start building the reed bed that will be used for treating our waste water. The reason for doing it in the winter is basically that this is the best time to transplant the reeds.

Our original idea with waste water and toilets were to use compost toilets in the house, and to recycle the gray water in the reed bed. Upon submitting the waste water application to the council we were contacted by them and asked if we would consider using normal toilets, and still use the reed bed for treatment. We actually did not know that we could put black water into the reed bed, but as it is quite dry where we live, this was recommended to us by the council, so that the reeds would both get more water and more nutrients. So, we then changed our plans a bit and will now be installing normal toilets in both the house and the guest house (possibly to the joy of some of our future guests), but we will select models that use as little water as possible. We are not likely to get back all the water that goes into the toilets (due to evaporation of water from the reed beds), but at least we will have most of it back, and it can be reused for irrigation of our fruit trees and berry bushes.

So, how does it work. The waste water has 4 main parts. First is a conventional septic tank which receives all of our gray (from wash basins, showers, washing machine, sish washer) and black water (from the toilets). This will work as septic tanks have for a number of years, with the liquid overflow continuing into the reed bed.

From the septic tank, the water first runs through a mechanical filter, then into stage 1 of the reed bed. This reed bed is filled with blue metal, mostly 7mm diametre, but some 20mm diametre around the inlet and the outlet to aid the water flowing in and out of the pipes. The reed bed itself is around 9m long, about 0.9m deep, about 2.3m wide at the top, and about 1.2m wide at the bottom. The total amount of blue metal is about 13-14 tonnes. Unfortunately we could not tip this directly into the bed, so we had to do it by hand (at least we got some good exercise!). The reed bed is then planted with reeds and the water runs through the blue metal and is "treated" by the bacteria that eventually forms inside the reed bed. With the size of the reed bed and the blue metal inside, it should theoretically take the water about 6-7 days to run through this stage one of the system. Important to mention is that the waterlevel is under the top of the gravel, so the top should remain reasonable dry.

Stage 2 of the system is an open, kidney shaped, reed bed. Water flows from reed bed number 1 via a 100mm PVC pipe, falls down on a pile of rocks (to add oxygen to the water) and then flows through the second stage. This stage is partly planted with reeds and there may also be some surface flowers, etc. but a certain percentage of the water should be clear to help the sun treat the water as it flows through. It will hold about 3500 litres and therefore should in theory retain the water for at least 7 days before it runs into the 3 stage, which is basically a holding dam (read: a big hole in the ground).

We are yet to plant the reeds in stage 1, but this should be done tomorrow, but here are some pictures of the full construction process.

Excavation of stage 1 completed	Installation of lining in stage 1
Waste water inlet to stage 1	Waste water outlet from stage 1, under construction
Outlet of stage one, completed	Stage one ready for planting
To ensure that the water level in stage 1 does not go to low, a control valve has been constructed. This uses a second hand toilet float valve, inside a PVC pipe with openings (underneath the balck screen above). A pipe is then connected at the bottom of the valve (black elbow) and connected to an external water source. If water falls below the wanted level, the float valve sinks down and water starts pouring into the reed bed. When full, the valve closes.
Stage 2, excavation completed	Stage 2, inlet completed
Stage 2, reeds planted	Stage 2, ready before being filled with water
Holding dam

We'll post some more pictures of stage 1, once we have completed the planting of the reeds.

Since last time we have also manage to get a washing machine. We did not have any place inside, so we made a little house for it outside:

And a final picture from a little walk we had last weekend. This is taken from the hill that is to the east of our property:

OH, and finally, congratulations to Mara and Anthony who just had their first baby girl !

Any problems, please email webmaster. This page was last updated 24/07/2008