Diffuser Basin Project Update

In the past few months we’ve mentioned a few times that we’ve been working on a project to make some changes to the “diffusion plate” in the filter. CAWST, after doing some studies, recommended that rather than use a “plate” type piece to slow the flow of water going into the filter, a basin or bucket type piece would be better. This would stop water from trickling down the insides of the filter, bypassing the the microbe attacking bio-layer in the sand bed.

Cross Cut Filter picture

The initial recommendation was to have the new diffuser basins manufactured by local people out of galvanized aluminum sheeting. After costing and researching Chris realized that would add $4-5 US to the cost of the filters. He also had concerns about the zinc in the galvanized aluminum being in constant contact with water. He started researching options and came up with the idea of making the diffuser basins out of injection molded plastic.

Working with some engineer friends, the initial drawings were made. He visited some plastics companies in Port au Prince to see what the options were and to get some preliminary costs. The only issue was having the funding to get the mold made so the basins could be produced.

As you might remember, we ran an Indiegogo campaign last December with a goal of raising $20,000 to make the mold. We didn’t reach our goal, and raised $7500. While we were running the campaign a future Vision Tripper contacted me and mentioned that he would like more info about the project, because he ran a mold and manufacturing company in Ohio that produced injection molds. He can Chris went back and forth, and within a week his company, Great Lakes Mold & Manufacturing, committed to building and donating the mold for the diffuser basins to Clean Water for Haiti!

Over the last few months they worked at producing the mold.

Diffuser basin mold bottom.
Diffuser basin mold bottom.
Diffuser basin mold top.
Diffuser basin mold top.


In early March the mold ran it’s first test samples of the diffuser basins. When Dave visited us for the March Vision Trip he brought those 5 samples so we could see them ourselves. They were beautiful!

The first five diffuser basins made with the mold.
The first five diffuser basins made with the mold.
Inside the diffuser basin.
Inside the diffuser basin.


It’s so exciting for us to see this project come to fruition. The basins made for the sample run were produced with recycled polypropylene and are more solid that we expected them to be. We’re using one in the filter in our house now and it works great! There are some minor tweaks to do on the mold to meet some new standards based on a recent study, but they’re simple.

While here, Dave and Chris visited the plastics companies again to get updated quotes and talk logistics. Our original intent was to have the basins produced here in Haiti, but while hashing out details another important factor came up – our goal with this project was to not only meet new CAWST recommendations, but to also make the mold designs available worldwide to other Bio-sand filter projects so they could have access to injection molded basins.

That in mind, we recognized that most projects would not be able to foot the $20,000 bill to have their own mold manufactured. Then there were the logistics of shipping it in to the country where they are working, and then finding someone that can produce the basins using the mold. Every injection molding machine uses different specs, so this can make producing the mold itself challenging.

Dave came up with a suggestion – keep the mold in the US, and have an associate of his who tested the mold actually produce the basins there, then ship the basins wherever they needed to go. Using recycled plastic will cost approximately $0.09/unit. We have already looked at shipping options, and we know that to ship them to Haiti we would be paying about $1.00/unit, so total cost to us and the projects we resource in Haiti would be about $1.09. Our current cost for the diffusion plates we’re using is $1.35/unit.

Going this route means we don’t have to worry about the mold not being maintained here in Haiti. The plastics companies are used to running batches in the 10’s of thousands, and our needs would be in the area of 5,000 units per year. Small beans for them. Dave would be able to work out any manufacturing issues with his associate, and do any maintenance on the mold as it came up. The biggest perk though, would be that projects from all over the world could have access to the diffuser basins by simply making an order and shipping the basins to their respective country, rather than having to have their own mold etc. One mold can service the world.

We’re really excited to see where things are going and to know that projects all around the world will benefit from this new technology. The Bio-sand filters already have a high level of effectiveness, this will just make them that little bit better!



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