9. Testing the Water at Pun Pun

In an earlier post I mentioned Pun Pun devised a relatively cheap water filtration system made by readily available materials so there is drinking water on the farm for everyone.

But what about the quality of the water? What do they do to ensure the water is safe to drink?

This missive is about how the water at Pun Pun is tested. 

First a review of the system. Here is what the water system looks like:

Pun Pun's Water Filtration System

Left to right: rocks get gradually smaller inside the tanks.
Last tank contains charcoal

Water is pumped up to the holding tanks and goes through the filtration process, as follows: 


Starting from the left, the first tank contains large pebbles. Water is fed from the top of the tank and is piped down to the bottom. With the force of gravity from the water falling down the pipe, the water is pushed up through small rocks, capturing large impurities before flowing into the second tank. The second tank contains sand. Water is fed from above the sand level and flows down through the sand, removing  microorganisms and smaller matter. Sand filtration is a good method to remove quite a bit more impurities and many pathogens, but is a little slower. A thin layer of microorganisms grows at the top surface of the sand, helping to capture them. Then the water is piped up to the third tank and falls through the charcoal filter. The charcoal removes the remaining chemical and pathogen residues, rendering the water drinkable.  

But how safe is it?

Every few weeks the water is tested for dissolved organic matter and iron. Samples are taken at the water source (the pond), then at the holding tanks, and then at each water filter tower. The samples are analyzed with a portable water tester. The resulting data are sent to Josh Kearns, Ph.D. candidate, at the  University of North Carolina where he further calibrates the results to keep accurate records of how well the filter is working effectively over time. 

Here is the method for water sampling and testing in pictures:

Nate Reents with the water sampling kit

Dipping the bottle in the pond

Taking a sample of the water pumped up to the holding tanks

Sampling the water in each filtration tank

Back in the main hall, calibrating the testing equipment

Filling the test tube with a water sample

Putting test tube into the equipment to run a test

Reading the findings

All the data are recorded so the changes to the water quality can be carefully monitored. Once the filtered water reaches a threshold of contaminants, it's time to clean out the filters (about four times a year).