How to test water for bacteria with the Coliscan Easygel E coli and coliforms test kit.

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Coliscan E. coli and general coliforms home water test kit.

What are coliform bacteria? First coliforms are a type of bacteria relatively common in soil and water. Some coliforms however come from the gut of mammals. And a proportion of these are usually E coli.Now E coli are not usually dangerous in themselves, they just indicate the possibiliy that there is fecal contamination of water. And again, not all E coli come from humans. They come from all other mammals.

The Coliscan test will give figures for the number of E coli and the number of coliforms in your water. You can then work out how many CFU's (colony forming units) per 100 ml. There are guidelines available for how many E coli and to a lesser extent coliforms there should be in drinking water or water which is used for recreation or for other uses around the home.

When should I use the Coliscan test? Use the Coliscan kit mainly as a way to assess the overall quality of your water. This is because each plate (you have 3 to work with in each kit) uses about 1 to 5 ml of water. Now it is possible that with such small samples you might just miss a few bacteria or you might get a few extras. So the Coliscan test has limits on its statistical significance. In other words you just need to be realistic and realize that although the Coliscan test is very good it will not tell you precisely, for sure if you do or don't have E coli in your water. The Coliscan test is better suited to testing your source water eg from a dam, creek bore etc.

If you absolutely positively must know if there is E coli in your drinking water then send in a sample to the Lab and we will do a special test called a membrane filter test which captures all the bacteria in a larger sample like 100 ml. (Note: Currently not available).

How to use the kits. The kits provide full instructions and a detailed guide on how to interpret the colours you will see on the culture plate and how to calculate how many colonies per 100 ml you have in your water. But here is a quick overview:

To use the kit fill the small sample bottle from a tap or by dipping it into the water below the surface. Keep dirty hands out the way. Take the pipette or syringe, whichever is provided and transfer a sample to the small media bottle. Of course be careful not to get your fingers on the pipette (it is sterile) or in the mouth of the bottle. How much sample? Take about5 ml if your water is very clean usually or 2.5 ml if its from a dam or creek.

This is a photo of a water sample tested with the Coliscan kit. The blue colonies are E coli and the pink colonies are general coliforms. Some other unidentified bacteria have showed up as well. The Coliscan kit makes identifying E coli very easy.

Mix the sample in the bottle then pour it into the petrie dish provided. -Now what has been hard so far? After about 45 minutes the gel sets in the petrie dish. Now you can put the dish somwhere warm like on top of the water heater or on a computer cover. Just nice and warm will do - and out of the sun. In about 36 - 48 hrs you should see enough spots to start counting.

Like to see how a step by step picture guide of how the kits work? Just click here Easygel step by step.

The Coliscan kit works in a clever way. E coli colonies show up as purple or blue spots and other coliforms show up mainly as pinkish spots. There is a picture of an E coli / coliforms culture plate in the Laboratory Analysis section of this site. Your instructions sheets will tell you how to distinguish the various colonies so you know what to count. This is the exciting part! The calculations are easy. If you used a 1 ml sample and found 5 E coli then there are 100 * 5 in 100 ml. For other sample sizes the instructions will show you how to do the calculations.

Are you ready to fly? We've used these kits for a couple if years and have been impressed by how easy they are to use and the usefulness of the results. If you run into trouble just contact us and we will help out. Checkout the help page for identifying colonies Coliscan Colour Guide.

There is also a step by step guide to using the Membrane filter kits. Check it out at ECA Check step by step. (Note: Currently not available).

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