Water Filtration Experiment

My original plan for this water filtration experiment was to do it for Earth Day, but things got too busy this year and we did something else instead (check out our posts for Homemade Seed Paper and Toilet Paper Roll Bird Feeders!)

Today ended up being just the right day for it. I had the right materials on hand, we were headed to the pond for a pond study, and Daddy came home from work early which always makes field trips a little easier. So we put together our filter and headed to the pond where we could get some murky water to filter. We are in the midst of a drought right now here in Central Ontario so we’ve been talking a bit more about climate change and how to conserve water. We are lucky to have running clean water here where we live, but not everyone is so lucky and drinking dirty water can make you sick.

The materials we used for our filter were as follows.

MATERIALS:

2 empty plastic bottles

knife or scissors

4 coffee filters

elastic band

sand

fine gravel

larger gravel

dirty water

I started out by cutting the bottom off of one bottle (this will be the filter) and the top off of the other (this will catch the clean water) so that one could fit into the other. The plastic and knife are both a bit sharp so I did this part. Then we attached the 4 stacked coffee filters to the opening of the top of the first bottle using the elastic band.

Next, the kids added the layers to the filter. First a layer of sand, then fine gravel, then larger gravel. Each layer was about 2-3 inches thick.

Next, Thomas mixed up some water in the pond to make it extra murky and then scooped it with a bucket. We filled the top of our filter and waited. Within a couple of minutes the first drops of filtered water began to drip into the bottom bottle.

We explained to the boys that the water is filtered through the different layers of sand and gravel to make it clear. But to be safe to drink it would still need to be boiled to kill any remaining bacteria or parasites. We also talked about how water is naturally filtered during the water cycle as water passes through sand, limestone and other gravel and rocks.

It took a while for all of our dirty water to pass through the filter, so we spent that time on our pond study. I brought along a large clear container, a scoop net, and some small buckets. I forgot our magnifying glasses but those would have come in handy too. We filled our plastic container with pond water first and closely examined what was in it. At first it didn’t look like much but when looking more closely, just this small sample of pond water contained many forms of life. There was some algae, a couple of small snails, a water strider, and a couple damselfly nymphs. All the life in this pond ecosystem depends on one another for survival. They are all part of a large food web and smaller energy chains which we studied earlier this year.

We were hoping to also come across some tadpoles today to examine close up, but we didn’t find any. We will head back to another pond for that another day. We did however come across a couple of frogs.

With our current drought conditions, we did also notice right away how much lower this water was than years past. It’s easy to spot since we frequent this conservation area often, and because we come often the kids are also able to see the way the area changes throughout the seasons.

Once we had enjoyed plenty of scooping and exploring the pond water, our filter had done its thing and we were left with a container of clear water from the pond. So cool!