HELP WITH MY SCIENCE PROJECT ABOUT WATER PURIFICATION

[Caitlin123]

I'm a grade 8 student doing a science fair project where I test how clean I can make water using natural purification methods (e.g. testing how clean boiling the water makes the water etc.) I'm using natural purification methods on dirty lake water from a nearby park. To test how clean the water is after I have performed each natural method on the lake water, I'm planning to use my TDS meter that checks for the total dissolved solids. I'm also using a bacteria kit that tests for coliform. I know that there are a bunch of other things that make water dirty, but is it fine if I just check for the bacteria and total dissolved solids? I don't want to purchase kits that test the water because they are pricey and I'm going to have to buy a bunch since I am checking different water. I REALLY NEED HELP. Can I change my science fair question around so that just checking for the bacteria and total dissolved solids will be fine? I really need an answer quickly and I would really appreciate it.

[deleted-249560]

If you're not too concerned on what the solids are (just the overall level), then your approach seems reasonable. The available kits might tell you what's dissolved in the water - which the meter can't tell you. It all depends on what your stated goal is, and how your experiment is designed. Remember that killing pathogens by boiling isn't always enough to make water safe. If you don't know what chemicals might be in the water, don't drink it even after boiling.

You'll find lots of information on how best to purify water with filtration and boiling in a web search. http://www.survivalgrounds.com/boiling_water.php seemed like a nice summary and there are obviously plenty of others.

[Caitlin123]

Thank you so much for the reply
But, I'm also testing different purification methods on naturally occurring water and I was just wondering if it would be acceptable if I just test how clean each purification method makes the water based on results from my TDS meter. Do I have to make the water drinkable or is it okay if I just test how pure the water becomes after I perform each purification method on it?

[deleted-249560]

You don't have to make the water drinkable, and indeed you can't really know unless you've tested for chemicals. If you say your project is about reducing dissolved solids and bacteria and demonstrate the effectiveness of your testing through data, you certainly can just do those tests and present it as a project. Depending on methods you're employing, the tests should show a reduction in bad stuff in the water. You say you're measuring for bacteria and solids - that's essentially what you'd expect to find and that is certainly purification. But if the water contains chemicals and you don't remove them (or test for them), you may still end up with water that's undrinkable.

I know the chemical tests can be expensive. Not doing them is okay, as long as you explain what you did, why, and what results you got. If you demonstrate a reduction in bacteria and dissolved solids, you will certainly have shown a significant purification effect.

[Caitlin123]

THANK YOU SO MUCH FOR THE REPLY! IT REALLY HELPED!
Now, I'm thinking about testing dirty water from a nearby creek using PH strips, my TDS meter and just by checking if it looks drinkable or not. However, I'm not checking the bacteria in the water anymore because the kit I purchased only says if it is drinkable or not based on the type of bacteria in the water, and it doesn't tell me the type of bacteria in the water. I'm really worried that this science project will not work since I am not checking all the things inside the water that is making it dirty. Is my current plan reasonable? Is there anything that I could change about this project to improve it?

[deleted-249560]

You mentioned that you were going to use natural methods to purify the water? Boiling is obvious, but did you have other tests in mind? You want to be careful about a few things:

1) To make water drinkable, it has to be cleared of everything that makes you sick. You're not testing for a lot, so you can't make that claim.

2) Just because something looks drinkable (more clear, smells better, doesn't have tadpoles swmming in it) doesn't mean it's even close to drinkable.

3) Just because your abbreviated test says it's drinkable, please don't actually drink it.

I can imagine it's reasonable to say "I started with dirty pond water and wanted to see if I do X and Y, whether it could be made drinkable. Here's what I did, and here's my data showing the results of test A and B. Based on the test results, the water should be (drinkable / undrinkable)". Demonstrating that you understand what was in the water to begin with, how you can remove some of the crud, what you would need to do to remove the rest and measuring how close you got seems like a solid project. You don't have to demonstrate commercial quality purification success. And since you may not achieve it - please don't make yourself sick!!

[Caitlin123]

Thank you so much for the help with my project ! I was just wondering if the title 'what natural purification methods work best?' is appropriate for this science experiment?

[deleted-249560]

If the experiment is about natural purification methods, then it sounds good to me. How many methods will you be testing? I'm not sure you said earlier, but you ought to include at least a few. Boiling is obvious - what else did you say you were going to try?

Howard

[Caitlin123]

I will be making homemade filters using gravel, sand , charcoal, leaves etc. and after each purification method is performed on each type of water, I will be boiling it. But I was just wondering, will boiling the water that has been purified using each method effect the results? I am afraid that it will change how clean the water actually is without boiling it. Should I boil the water after it is purified?

[deleted-249560]

I don't know how your specific dissolved solid meter works. It's possible that boiling will break up some of the solids and make them invisible to the meter, or it may break up larger ones and make them visible. I'm not a water quality expert and your meter is probably not some laboratory quality device (just guessing).

That said, I don't see that it adds a lot of extra work to your experiment to measure the water before filtering, measure afterwards (before boiling), then boil and measure again. I would certainly expect that the boiling will kill any bacteria and protozoa (although I guess we don't call them that any more) and make the water 'safer', regardless of the measurable solids. Since you're not planning to measure bacteria any more, you won't see that effect but maybe it will affect the solid count.

I'll hypothesize that the dissolved solid count will be pretty much the same before and after boiling. I'd be curious to know if that's right. Boiling will help the water release any dissoved Co2 though, so it may raise the pH ever so slightly.

Howard