The one device you can't do without for serious water sampling

I am of course talking about the depth sampler. If you want to collect a water sample at a given depth, you simply need this standard piece of equipment. Depending on the length of your rope, it can easily go down to 100 feet and beyond.

You can suspend this guy from a surface craft (e.g. kayak, motor boat) or a bridge overlooking the water body of interest. Once you have reached the desired depth as indicated on the marking on the rope, you release the messenger (a metal weight) which rushes down along the rope towards the sampling bottle. Upon hitting the bottle's "trigger", the 2 ends snap shut like a fish trap to enclose your water sample within the bottle.

Purchase Considerations

1. Alpha (aka van Dorn) vs. beta (Kemmerer). Alpha samplers are not recommended for chemical analysis (trace metals and organics) of the water sample due to possible cross contamination (mercury, phosphorus) from the materials in its construction (seals & closure tube). For chemical analysis, one is advised to use a beta sampler.
   
2. PVC vs. acrylic. Whether alpha or beta, the bottle body can be either made of PVC or acrylic. PVC is opaque but durable while acrylic is clear and less durable. If you need to see the contents within the sampling bottle, by all means, go for acrylic.
   
3. Horizontal vs. vertical. A horizonal sampler means the sampling bottle descends into the water parallel to the bed. Water enters from both sides of the bottle. This is useful for sampling at the thermocline, other stratification levels or just above the bottom sediment. A vertical sampler on the other hand descends with its body perpendicular to the bed. Water flow is not restricted during descent, making it desirable for collecting plankton and suspended sediments.

Figure: Lowering the depth sampler into the water body of interest. In this case, we were using the alpha, horizontal, acrylic version.

Figure: After retrieving the depth sampler, the water sample was drained into a suitable container.

Water quality workshop for water filtration company

The regular followers of my blog should realise that most of my workshops are geared towards schools, whether for teachers of students. I have recently conducted one in collaboration with Singapore Red Cross and Lifelong Learning Council though.

But this time round, I organise a water quality workshop for a water filtration system company. Interestingly, the attendees were staff from sales & marketing, admin, installation and management. Quite a mix of job functions and technical background! Challenging for a trainer but nothing I have not seen before.

Regardless, the rules of pedagogy still apply. A trainer or facilitator should always present materials of use and interest to the audience. In a chemistry class, chemical equations of reactions in water are ubiquitous but to a sales staff (and his customer), the same equations become Greek and frankly of little use.

And whether in a chemistry class, public workshop or private workshop for a client company, it always bring satisfaction to a trainer when he sees his learners motivated to know more and keen to try out the newly acquired skills. In that sense, trainers (and learners) are perhaps not that different despite the differences in subject matter, background and current levels of knowledge and skills.

Figure: A practical session in water quality testing within the company's premises. No, those participants looking outside the window were not admiring the scenery. They were using the colour comparator (not visible) which needs a good souce of lighting e.g. daylight.

Worried about lead? Here's a simple test

Lead in tap water was mentioned in some of my earlier posts - 1, 2. Essentially, SG tap water is relatively safe when it comes to lead. "Unless you happen to live in a really old building which still retains its leaded pipes over the decades... and unless somehow your building falls under the radar of the extensive sampling and monitoring programme... then maybe you should be worried."

Nevertheless, I had a concerned reader contacting me about his worry of lead in tap water because he bought a water faucet over the net from Taobao. Apparently, he read (only after buying the faucet) about lead being used in fabrication of the faucet. With online shopping becoming more common now, who even knows much about the product one bought? Where are the parts from? Are they certified safe? Are the accreditation standards different from SG?

But I hear you say that it is SO convenient to buy online. Indeed it is. I too buy lots of stuff online...

Anyway, back to lead...

In another post, I recommended this product to test for lead in water painlessly.

PurTest DIY Lead Water Testing Kit. USD16.95

I chanced upon another similar product but of a different supplier on Amazon and got 2 tests for SGD33, inclusive of delivery.

Figure: Test kit for lead from USA. About as foolproof as a test kit can be.

Figure: The testing materials are all packed in a foil package. Open it only when you are ready to test your water.

Figure: A workshop participant residing in the Havelock area was concerned about lead in her tap water as her building was really old, say 40 years or older. An aliquot of her tap water was placed in the plastic container (part of the test kit) before dipping the test strip inside and waiting for 10min.

Figure: Just like a pregnancy test kit! The pattern of the 2 lines - 1 faint, 1 dark, indicate a negative result. As usual, such a test only tells you YES or NO or in this case, whether the lead level has exceeded the safety level. Do keep in mind that this test kit is designed for USA with a safety level of 15ppb (parts per billion) whereas SG follows WHO standards which stipulate a safety level of 10ppb. Nevertheless, I am not going to get a stressed up over a difference of 5ppb. If the lead level is safe enough for USA, it is good enough for me. Still, doing the test 1 or 2 more times and getting a negative will improve my confidence in the water's safety.