In 2018, through some research online, I had a very simple DIY greywater treatment put together on two sections of the garden. One for kitchen greywater and the other for bathroom (sink and shower) greywater. Today, I took some videos and photos to show how it’s all working after 6 years.
The grease trap is still in good working condition. I only had to replace the plastic sieve on top twice because they got brittle and broken from exposure to sun and the stress of cleaning them.
Most of the plants I planted in the infiltration planter died. They weren’t suitable for greywater. The best plants for this type of water are these that can be seen in the video, most notably: Brazilian Red Cloak (Megaskepasma erythrochlamys), Costus Igneus (Insulin Plant, Chamaecostus cuspidatus, common name fiery costus or spiral flag), and Sunset Bells (Chrysothemis pulchella).
The water that flows out of the infiltration planter goes into a ground level planter and the video also shows a greater variety of plants that thrived really well. It took some patience trying out all sorts of plants in these locations to see which ones loved growing in greywater. It was worth the patience.
Update on the for DIY kitchen greywater treatment
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BATHROOM GREYWATER TREATMENT
I had some soil dumped on the cemented gravel path where the bathroom water goes into. These plants grew remarkably well. I have not replaced the gravel or cleaned anything up.
The household is composed of only two persons, so our wastewater volume is not very large.
Best growers were the Brazilian Red Cloak (Megaskepasma erythrochlamys) and Costus Igneus (Insulin Plant, Chamaecostus cuspidatus, common name fiery costus or spiral flag), rising to 10 feet tall.A closer look at the plants growing. The flowers are Sunset Bells (Chrysothemis pulchella) and they too love greywater.The bathroom greywater goes through the planter, the gravel path, then some4-5 meters into this pond. I think the water volume is not really large enough to reach the pond.
We had plumbing repaired in May and that also became the opportunity to find a way to treat domestic wastewater so that it can be diverted into the garden. Since sewage systems aren’t centralised in our village, it is important that we treat our wastewaters locally and in a way that is responsible.
Plan for Infiltration Planter
Plan for the Gravel Path (sand was omitted)
Plan for Gravel Path
Plan for Infiltration Planter
Above: Some of the drawings and plans we made to help build our greywater treatment systems.
In households in our village, domestic blackwater goes into a septic tank whilst greywater goes into the nearest empty plots. We have our own septic tank and our greywater went into a concrete water feature in the garden. This water feature often flooded especially in the rainy season, and wastewater just filtered into the ground. What we wanted was a system that not only filtered greywater, but also diverted it to good use in the garden. Additionally, we decided to separate kitchen greywater and bathroom greywater to lessen the load on our selected methods of treatment.
Treating Kitchen Greywater
Kitchen greywater goes though a pipe and gets filtered in a DIY grease trap (refer to links to resources below to learn how to make a Grease Trap). From the grease trap, the water pours into a constructed wetland – or what may be called an infiltration planter – built next to the rainwater fishpond. The infiltration planter is filled with layers of gravel, a fine mesh netting, sand and soil. Plants are grown in the infiltration planter to help treat the greywater. As greywater filters down the planter, excess water flows out into a lower bed of plants.
View of the Grease Trap.
Grease Trap – bucket with strainer on top to filter out food debris. Refer to links below on how to make a Grease Trap.
Accumulated grease in the Grease Trap.
Internal construction of the Grease Trap – elbow and pipe sealed with Epoxy.
Grease Trap is cleaned next to the compost pit.
Treating Bathroom Greywater
Bathroom wastewater consists of water from the shower and the bathroom sink. This water goes through a pipe and flows out over a gravel path with cement lining to prevent the water from seeping directly into the ground. The gravel path goes along the house, into the garden and down to the duck pond, some 10 or so meters away. The assumption is that the greywater – along with rainwater during the rainy season – would be filtered appropriately by the time it reaches the duckpond, at the same time reducing soil erosion, since the ground slopes naturally towards the duckpond.
Ground has natural slope and the Gravel Path Filter is dug up in the direction of the slope towards the duck pond.
After digging, the path is cemented to prevent water from seeping into the ground along the house. The water needs to flow and get filtered by the gravel and ultimately flow into the duck pond.
Gravel placed into the path. The orange pipe is the bathroom greywater outlet.
A closer view of the Gravel Path Filter. The reservoir/pond catches rainwater runoff from the roof of the house and overflows into the Gravel Path Filter.
At the end of the Gravel Path Filter is the duck pond. Rocks are placed at the mouth of the Path to filter out larger debris.
The results
After nearly 3 months of use, together with the onset of the rainy season, our constructed wetlands are working beautifully! Plants are growing well in the infiltration planter, the gravel path has done away with mud and soil erosion in a large area along that side of the house. Some plants and grass have even started growing amongst the gravel. There is some odour coming from the infiltration planter but this is not irritating and the odour disappears very quickly. As more plants grow in the planter, we hope the odour will be further minimized. The DIY grease trap – a 5 gallon/10-liter capacity -requires some cleaning only every 2 months. The grease and debris collected is dumped into the compost pit.
Note that if any edible plants are placed in the infiltration planter, they should not be eaten.
Resources
If you are interested in building a constructed wetland system for greywater treatment in your own home, check first with local ordinances. Some municipalities, for example, that have centralised wastewater treatment facilities will not allow domestic greywater treatment because centralised wastewater (especially blackwater) treatment needs sufficient amounts of greywater for proper treatment.
If you are sure that constructed wetlands are allowed in your location, you can find basic information, designs, principles and examples of ecologically responsible wastewater treatment systems through the following resources. Our home set-up was inspired by these resources. Good luck!
