Singapore Polytechnic-Second Water testing

The second testing of the water samples brought back by the recce group was held on 11th July 2010. 6 of us made our way down to SP in the morning to finish the tests for COD and Ammonia.

When we arrived, we were given a brief introduction on the COD test, which was the more time consuming test to do. Firstly, we had to prepare a mix of the different samples with the COD solution. Next we had to leave the solution to heat for 3 hours. After that 3 hours we then had to put it in the machine which would give us the reading.

During the 3 hours wait, we conducted the ammonia tests on the water samples. The ammonia test was considerably simpler and faster. First we filled up the small container with the sample water. Then we put it in the machine to get the zero reading. Next we put the first reagent, mixed it, then the second reagent. After that, we put in the machine for about 3 minutes, then we record the reading.

At the end of the session, we collated our results and Dr Liu explained what the results actually mean and gave us possible reasons for our results. It turned out that we had made a mistake somewhere during the COD test and all our results were wrong and useless.

It seemed that the nitrate levels from almost all of the water samples were relatively safe for consumption, the exception being water from both wells. It was also a bit strange that the water from the river contained such little nitrates. This was strange as rivers are usually the targets for waste excretement etc. Dr Liu explained that a possible reason for this anomaly was the collection of the sample. He said the sample should be collected right in the middle, between the surface of the water and the bed. When checked with the recce trip group however, they were unsure where the water was collected from as it was collected by a villager. He also explained that a possible reason for the water sample of both wells to possess so much nitrates could be due to villagers' horses excreting near the well, or villagers dumping waste into the well.

At the end of the day, it honestly felt like a wasted day due to the unusable COD results. The COD tests were the longest tests and all of us were very careful with the tests. Yet, in the end we still overlooked something and messed up the entire test. However, looking back, the day was not entirely wasted as we did manage to complete ammonia tests and learn a little something about water standards and what is required for water to be able to be drunk.