Overseas community service (OCS)/ Youth expedition project (YEP) part 3: Are there still more things to check if my water is safe?

This post follows from 2 previous posts.

1. Overseas community service (OCS)/ Youth expedition project (YEP) part 1: Is that water safe?
2. Overseas community service (OCS)/ Youth expedition project (YEP) part 2: How do I know if that water is safe?

So you have checked out your watershed and everything looks ok. No industries, agriculture or villages around. Are we home and dry?

NO! We have not checked out the history or to be more exact, the geographical history of the watershed! Find out what the area used to be...

2. Historical geography

Example 1: Mining
Mining (granite, coal, metals etc.) can especially be nasty to health and environment even after closing down for years. Digging deep into the earth can release toxic substances (lead, radiological compounds, heavy metals etc.) found underground into water once the mine fills up with water after closure. Not surprisingly, mining can also impact groundwater quality so those looking at using well water do take note as well.


Or sometimes, the mining operation itself left hazardous waste which remains uncleared after closure.

Google "toxic legacy of mining" and you can find tonnes of examples. Here are a couple.

1. http://www.abc.net.au/rural/news/content/201102/s3142796.htm
   Australia - copper and gold mining can create a leachate with hazardous levels of copper, manganese and zinc.
2. http://keeptheban.org/?p=678
   France - uranium mining - "accumulation of radioactive metals in sediments and plants of rivers, ponds, and lakes by contamination around former mine sites has also been found to have high enough contamination to be considered “radioactive waste”"

And a common example is acid mine drainage in which sulfide ore from underground turns into sulfuric acid upon reaching the ground surface (chemistry is involved). This can be quite serious as it can turn water very acidic - pH of 1 or less.

Example 2: Agriculture
Depending on the type of agriculture, you can find different pollutants in the soil or sediment. And these pollutants may subsequently leach into the adjacent water bodies. If the pollutant load in the soil/sediment is heavy, the leaching can occur over a long period of years. Short of dredging the entire load of sediment or bulldozing the whole lot of earth, the problem can only be treated symptomatically without eradicating it source. (See a potential case study in a previous post - How to get rid of your seemingly unstoppable pond algae at Sungei Buloh.)

If we are talking about crop land or plantations, there is a likelihood of pesticides and fertiliser residues in the soil/sediment. On the other hand, animal farms will likely introduce animal waste (which is also a source of nutrients) into the soil/sediment. Nutrients/fertilisers are especially good at promoting eutrophication in water bodies while pesticides can be toxic to the ecology and us.

Most of you probably knows that Sungei Buloh used to be house prawn and fish farms in its mangroves before being converted into the wetland reserve we know together. However, do you know that it used to house pig farms too? (Wetland forest of Sungei Buloh mangroves) Has all the pig waste been cleared from the area? If not, can this be a source of nutrients leaching from the soil/sediment into the current mangrove area and causing eutrophication?



Example 3: Estuaries
In simple terms, an estuary is the intersection between a river and the sea. It can be in the form of a swamp, bay, delta etc. Not only does it accumulate (depending on the tidal and hydrological conditions) stuff from the river (think about oil, pesticides, heavy metals), it can also receive pollutants from shipping (ballast, waste, cargo overboard), especially along a busy shipping channel or near a port.

The port and upstream factories may not be there anymore but the pollants remaint in the sediment, possibly for a long time of decades and slowly releasing its toxic load of heavy metals and persistent organics (including dioxins, PCBs (polychlorinated biphenyls), -cides (pesticides, insecticides, herbicides)). BUT if someone decides to dredge the sediment (perhaps to keep the channel deep for shipping), you may see the serious problem of a massive dosing of pollutants into the water. Morale of the story: don't disturb the sediment unless you intend to remove the whole chunk as a long term solution.

Incidentally, heavy metals or persistent organics can show up in bottom feeders such as shellfish (mussels, clams etc.). They accumulate the substances as they wade through the sediments for food. Of course, what this means is they are potential bioindicators - indicating the health of the environment without doing a chemical analysis first.

The other more serious implication is if the locals feed on these bottom feeders, they may very well be intoxicating themselves.

Figure: 1969 topo map of the area around Ngee Ann Stream. Notice that the old railway track splits into 2 lines near the Bukit Timah station. Old maps are a good source of information on the geographical history of the area. Another source is old aerial photographs.

Figure: Google Earth view of the same Ngee Ann Stream (imagery data 2009, 2010). Some roads and waterways remain after all these years.

Figure: Photograph from The Straits Times, depicting the floods in 1978 and men rescuing their pigs. More importantly, it tells you that Woodlands, Braddell Road, Potong Pasir to Changi used to be a "farm belt". Such old news are another source of information.

Figure: Quarry lake on Pulau Ubin. Disused after the granite quarry has closed. How does such a mining activity affect the water quality?

Overseas community service (OCS)/ Youth expedition project (YEP) part 2: How do I know if that water is safe?

For those working in developing countries:
In case you are still not sold on the idea of drinking from rainwater based on my previous post (Overseas community service (OCS)/ Youth expedition project (YEP) part 1: Is that water safe?), read on. Incidentally, some communities do not want to drink rainwater because of tradition and culture. They have drinking from surface water (ponds, rivers, lakes) since the time they were born, they do not see other sources of water as viable. Depending on the situation, you may not want to fight an uphill battle to suddently switch their drinking habits to a rainwater source. Perhaps, you may be better off convincing them of implementing some treatment method.

I have been consulted by organisations which want to operate in developing countries and know more about the safety of their drinking water. An approach similar to the one below may be used.

1. Geography
If you are collecting surface water, know what is upstream. (This was covered in the previous OCS/YEP post but I will add some more information here.) Residences, villages, resorts, tourist attractions or heaven forbid, industries and agriculture upstream should light up a big red flag with a buzzing alarm... Drink the raw water at your own BIG risk.

But knowing the land use should extend to more than just along the waterways. Know your watershed! (In Singapore, we call it catchment basin or drainage area instead.) Your watershed is basically the land area acting as a big umbrella to catch and convey the rain to your water point. It includes the forests, parks, carparks, roads, other built up areas for the rain to flow over before reaching your water collection point. Naturally, any substance (e.g. litter, oil, animal droppings, soil, minerals) on the ground surface is fair game for the rainwater to pick up as it flows to your water point.

So you say that your river does not flow past any industry but if your watershed has a leather tannery or beer brewery, their waste chemicals may find their way into your river (and your mouth if you are drinking from the river).

Traditionally, we use topographical maps to delineate the watershed. In simple terms, water always flows from high to low points. Join up all the high points surrounding your water collection point and you have set the boundaries for the funnel into which water flows. (You may refer to Georgia Adopt-a-stream file here for a better description of the process. In fact, I strongly recommend that website as it contains a lot of useful information for water quality monitoring.)

However in current times, computer software and GIS (geographical information system) are used to calculate the watershed.

Of course, you may not have a topographical map. (Some countries consider this a state secret. Even in Singapore, it is not easy to get one.) Much less the digital map for your area of interest. Then the next best method will be to check out the areas adjacent to the waterway upstream of your water point. An area 1-2 km from your waterway will be a good start. Same as before, check out the landuse patterns in these areas. Does anything stick out like a sore thumb?

Figure: Sample topographical map. Useful to delineate your watershed if you don't get overwhelmed by the amount of details in the map. It also tells you quite a bit on the landuse in your watershed.

Figure: Students' rendition (sketch) of the landuse patterns around Ngee Ann Stream

To be continued...

Overseas community service (OCS)/ Youth expedition project (YEP) part 1: Is that water safe?

Our students are really lucky these days to have many opportunities to go overseas. We have acronyms like YEP (youth expedition project) (funded by MCYS), OCS (overseas community service), OCIP (overseas community immersion programme), OITP (overseas industrial training programme) plastered around campus, encouraging our students to sign up. In addition, we have more of the overseas outdoors variety of activities e.g. leadership camp, adventurers camp, mountain climbing, too.

Especially for YEP/OCS where the participants (students & staff) get to live close to the community they serve (read rural and undeveloped), they will stand next to the pond/stream/cistern/faucet/pail (take your pick) and ask, "Is that water safe?" Unfortunately, the answer may not be so straightforward.

Let's answer that question with another question, "Safe for what?"

For the brevity of this post and the significance of the intended use, let's restrict ourselves to "safe for drinking".

Water quality (WQ) parameters
If you are going to test the water according to WHO drinking water guidelines (more about the testing of water in an earlier post), you are going to find yourself wading in deep cess. You have close to 200 WQ parameters to test and the a complete set of tests will burn a big hole in your pocket. Fortunately, I can share some tips here to make your judgement easier or at least drastically reduce the kind of tests you need to make.

Sources of water

1. Rainwater
   This is the cleanest form of natural water. The processes of evapotranspiration and condensation in the water cycle is effectively a form of distillation. The only concerns will be air pollutants (e.g. acid gases, particulates). Acid gases will of course make the water acidic while particulates may contain heavy metals that go into rain. But the effects are likely to be small compared to the potential problems encountered in the next few sources. Hence, I would still put my bet on rainwater as a viable drinking water source among the various natural sources. This is also why I strongly advocate rainwater harvesting in communities that lack a reliable and safe source of drinking water.
2. Surface water: Pond, stream, lake
   I would check (ask the locals, check the map etc.) the upstream and the surroundings. Are there residences, industries, agriculture or other human activities? These can release human waste, animal waste, industrial waste, pesticides and other nasty stuff. Unless near the headwaters (usually thick jungles in the tropics), surface water tends to be turbid and contains an unhealthy does of bacteria. These are 2 good WQ parameters to measure if you still want to use surface water (perhaps combining with some sort of treatment). And if there are industries and agriculture around or upstream, you can add heavy metals, pesticides, oil, detergents, fertilisers into your to-do list of WQ testing.
   
   (Digression: Incidentally, I have seen outdoor activities being conducted with the participants immersed in a river (i.e. primary contact) in other countries. Hopefully, the organisers have bothered to check what is upstream of that river in case the participants gulp down mouthfuls of river water containing human waste from the village upstream.)
3. Groundwater: well, spring
   Generally less turbid and has less harmful bacteria than surface water. However, it may contain heavy metals (e.g. lead) that occur naturally in the ground. Depending on presence of arsenic deposits in your area (developed countries e.g. USA are not spared either), your groundwater may contain a dangerous concentration of arsenic.
   
   On the other hand, the presence of human activities e.g. industries can also lead to leaching of toxic chemicals (think organic solvents, pesticides, electroplating wash) into groundwater. This is especially true if the industry does not have a habit of cleaning up their act e.g. dumping waste into the ground like nobody's business instead of treating or sending it for proper disposal.
4. Man-made outlet: faucet, cistern
   
   Hey, the water must come from somewhere right? Is rainwater harvested and stored in the cistern? Or is there a pipe that conveys the water pumped from a well or stream? Maybe the nearby spring is diverted to come out from the faucet?
   
   Make the effort to find out the origins of your water and see if they come from any of the above 3 sources.
   
   Finally, your community/village may be lucky enough to have piped water from a water treatment plant! This may or may not be good news though. For one thing, it is hard to tell if the water treatment plant is doing a good job without doing any actual WQ testing. The locals may be able to advise you but then again, their bodies may have adapted to the water (clean or otherwise) and some effects do not appear in the short term.
   
   Note that not all water treatment plants are built alike or at least they are not built like our PUB plants which are considered effective and produce water of adequate drinking standard. I have heard of water treatment plants in other countries that add massive doses of chlorine to kill the germs but do little else to clean up their water. Well yes, you have germ free water but that heavy dose of chlorine will probably give you cancer years down the road.

I will continue in more future posts on this topic

Figure 1: Sand filter at our local water treatment plant at Chestnut Drive (see previous post).



Figure 2: Binjai Stream - this part is close to the headwaters so the water is relatively clean and clear, flowing over a sandy bed.



Figure 3: Ngee Ann Stream - this is further downstream from the headwaters. Note the obvious turbidity.