Swee Yong

Just an idea.  We know that waste water can be treated in a wetland using reeds and wetland plants to clean out the water.  Could the same be done using banana trees in a horizontal subsurface flow CW?  Instead of planting wetland plants on top could you plant banana trees instead.

I know that there has been a lot of great success with permies and natural farmers applying the banana circle and mulch basin concept.  Directing the flow of grey water in to the much basin and having the banana plants suck up all the water.  I would assume the excess water would percolate through the mulch and soil and into the ground.

Would it be bad for the soil if the grey water were to percolate and be absorbed into the ground? Or would it be better for the grey water to pass through a gravel filter system similar to a constructed wetland before being released in to the ground or water way.

I havent came across any information on whether bananas actually help to purify the water just like wet land plants do.  Does anyone know?

Banana circles and mulch basin.  Have you considered it.  

Yeah I dont think it would be possible to direct the urine into the grey water system unless we have a separate urinal and closet.  

Any take on the trench idea/ wicking bed/ subsurface CW? If grey water is kept in the threshold of the resevoir (gravel layer) will it habour more disease and bateria and cause the water to smell?  The only time the water will over flow is if the water level rises.  The water in the the reservoir would be able to supply surface plants water just like a wicking bed whilst purifying the water.

Currently checking out grey water action org and lopking for details on mulch basin design and how to prevent clogging of system.

I am looking at building one cause we cant just dump out the grey and black water due to lack of municipal facilities.  

Idea is to build a series of trench total length 300m long with plants planted in the top to help with filtering the grey whilts providing nourishment for the plants.  once the trench is filled up past the resevoir level it will eventually over flow and fingers cross the water will eventually be clean and safe enough to be release into the ground. Though I could be wrong and create major mess.

Tobias Ber wrote:heya.... would it be possible to divert the blackwater from the greywater?
by using urine diverters and male urinals (duct into the greywater) you might reduce the amount of blackwater even further.

there s a system (there are posts here on the forums) where the black water drops into a container with woodchips and compost worms. after that the water could be treated by a sedimentation chamber or swirl filter and the a reed-bed (or go directly into your greywater system).

i think, a long and narrow ditch/trench along the perimeter of your estate would be a good thing for the greywater. and and multiple small units (a pond/wetland with trees, reeds, bamboo etc.)

I keep hearing about using wood chips.  Would this be the first stage of the system whereby the grey water enter first, gets filtered by the wood chip and mulch and earth worms (would the grey water be safe for earth worms?)

I am thinking of combining the idea of subsurface CW with wicking bed though I think the principles of both systems are relatively the same.

Hi.  Great idea for using the grey water for wicking bed.  I did read somewhere that grey water was not recommend for wicking bed.  I dont know why. Only reason I could think of was the water not being safe for the plants or if you plan to eat the fruits or the produce from the wicking bed.  Second maybe because it may smell as the grey water is stagnent in the reservoir.

I assume a wicking bed is not much different to a subsurface constructed wetland.  Grey water is channelled subsurface through a gravel layer.  Top layer is planted with plants whose roots absorb the nutrients either through a wicking effect or direct contact by roots.  

I am located in the tropics as well and would like to build a subsurface CW for my property however I am stuck on the depth of the gravel layer, sand, and soil.  some do it this way and some that.  

Anyways I hope it works out.

P Lyons wrote:What area of Indonesia.  I spent 3 years there.  I sent you a PM with some contacts that are involved in the types of development you are considering, they all happen to be based in Bali, but they likely have contacts in other regions as well.

Small world.  We are looking to build on an island next to Bali called Lombok. I just went through and checked all my calculations again.  I put down 15 min while the average show time is between 7-10 mins.  So that made a huge difference in the water usage.  Plus the room do not have bath tubs so no wasting water there. So it comes in at 250 L per person.

The way hotels count their water consumption per room is based on the occupancy, a king room with single occupant as to a king with 2 occupants.  In that scenario you would base the water consumption on 1.75 times occupancy mulitply by the average percentage room occupancy rate per month.

However in my case its a little different.  Sure I can calculate base on assumptions and target however what is certain is the hotel will most likely be operating at full occupancy plus extra guest once in a while.  Which means its better to take in account the peak rate and design the system around those figures.

Peak water usage comes in at 29,800 Litres grey water and 9000 litres black water.


I am little concern of channelling all the grey water into a subsurface type filter.  Whether the water will be safe for the environment.  I believe the size of the trench and volume is more than capable of absorbing 3000Litre in 10 min and handling the rest of the 27,000 litre of water through put the day.  

I better talk with your contacts.  Cheers for the head up.

Vlad Alba wrote:We use clumping bamboo in an outdoor shower that sees regular use. The bamboo gets all the shower water. it was planted in a little pit where the water drains into. The bamboo is very happy.
We're in zone 9a with well draining silty loam. The bamboo spreads only very slowly and would be easy to keep at bay.

Awesome.  How about the root system do you have to dig it up and clean out the root system?
I am thinking of doing similar for my project.  How does the bamboo handle soap water from the shower?

Great Point

There are several possible advantages of this strategy:

- You may be able to save significant cost on plumbing materials and installation compared to conventional collection plumbing of all facilities to one treatment area.  
- Each system could be designed specifically for the type of greywater to be treated, and would make planning for daily flow rates and peak events would be simpler, with less risk of over or under estimating the actual flows.  
- smaller easier designs for planning, installation and maintenance - would also be able to be more discretely incorporated into the landscaping plan
- facilitate future alterations to the system as individual areas can be maintained/modified/expanded on a smaller simpler scale.  
- Easier troubleshooting of system issues
- mitigation of system failures.  If a combined system fails, the entire resort is affected, where as individual system failure would only affect those locations where the issue has occured.


Something I did consider was having a valve that i could direct the grey water to the septic as back up.  But that means I would need a larger capacity septic.

Peter VanDerWal wrote:Well you can run through the formulas, etc. but generally speaking you want a large enough "Constructed Wetlands" that can contain about 5 days worth of grey water, this is to ensure that the water stays in the wetlands long enough for the plants and bacteria to process most of the BOD.
The gravel is going to take up at least 50% of the containment area, so you'd need something large enough to hold about 150,000L
1 meter depth is fine, but it's gong to need to be a LOT wider than 50cm, probably going to need to be at least 4 meters wide.  Most recommendations say to make the wetlands square, but I've seen some studies that indicate the wetlands that are up to 10 times as long as they are wide work just as well.

Here is a design guide by the US EPA (Design Manual: Constructed Wetlands Treatment of Municipal Wastewater), it's a little conservative in some areas, but has a lot of good info

https://www.epa.gov/wetlands/constructed-wetlands

Yeah we dont have the land for Constructed wet land. We only have 7500smq.  I did have an idea of filling up the parking lot with a layer of gravel and sand  .5 - .8m in depth.  Parking lot is 400 sqm which would be about 200m3 volume.  The water would just percolate into the soil beneath. I just want to be sure that I am not polluting the land and want to be sure whether the intial filtering through the gravel and sand was sufficient enough to bring the grey water up to safe levels.  Or whether this route is no the right solution  or whether there should be some pre-treament first.

Thanks for the input.