Testing kits for E Coli in beach water

Some_randomer

Calling all scientists / engineers, hope I'm in the right place. I'm looking for a beach water testing kit that can monitor and test for E Coli on an ongoing basis according to the www.epa.ie spec for beach water safety. It would need to be deployed and work continuously in water (as opposed to on land). Would also need to have some kind of port / interface to retrieve the test result data.



Does anyone know if such a thing exists? All I've found so far is manual testing kits that work on land and take 48 hours or longer to produce results.

Some_randomer

After doing a lot of googling it looks like detecting E Coli takes time and needs to be lab based. The only thing I found was a research paper from 2017 where some people created a litmus paper test whereby the paper is dipped in water being tested, and a change in colour of the paper indicates the presence of E Coli:

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0183234

So now I think I need to change tack. I'm from an IT background and not a scientist so don't know if I'm on the right track, but someone told me that a change in properties such as oxygen and salinity in water might indicate the presence of contamination. Temperature conductivity was also mentioned.

I'm pretty sure kits for detecting changes in oxygen and salinity levels are available, so does anyone know if changes in these properties would indicate possible contamination? Or any other changes that might indicate contamination that could then be further investigated?

AngryHippie

There are too many variables that can result in oxygen level changes.

There are some laboratory sensors that can test levels, https://cosmosmagazine.com/chemistry/a-quick-easy-test-for-e-coli-contamination

But there is no field test that can give you a fast answer.

What is the application and why ?

Some_randomer

Thanks for the link that looks interesting and pretty much what I was looking for. According to the article it's still lab based but they're hoping to miniatuarise the equipment so it'll work in the field.

I'm doing this for a project like in the link where we're trying to provide more timely notifications for E Coli in bathing water. Currently it could take several days to determine if there's been an E Colli contamination from a sewage spill or whatever. So I had an idea of creating a kit that could monitor for E Coli on an ongoing basis. It seems like this isn't possible as the water needs to be tested in a full on lab and takes 48 hours or more.

My next thought was to monitor for changes in properties like pH, salinity, oxygen levels, turbidity or any property that might indicate the presence of E Coli. So I suppose my question now is if there's any property where a change to that property might indicate an E Coli contamination?

AngryHippie

In a controlled lab environment yes - In the sea....no chance.

Far too many variable inputs from rain to fish farts that could have a greater impact than e-coli at the levels that you want to monitor.

In general its more practical to monitor the source of the pollutant (the wastewater treatment outlet), which might give you some lead time before it hits the beach, but that discharge will have been designed based on a flow and dilution basis anyway (B.O.D) all of which are also variables.

All of this will be further complicated by off-grid sources (Farmland run-off, bird colonies etc.)

There will be no practical way to monitor it in real-time as the detectable thresholds require giving them a chance to multiply (at a known reproductive rate at a given temperature for a given period of time) and working the numbers backwards to give an original sample concentration with a margin of error.

It's an interesting idea, the reality of creating such a kit or device will be heavily reliant on some expensive equipment and will take a lot of engineering and design to miniaturize and make watertight for a marine environment.

Sensors for salinty, oxygen level, CO2, pH, temperature, turbidity etc. exist independently and in multi-meter combinaitons, but are all subject to sensor drift and require regular calibration and maintenance, so once again you are back to the ongoing cost of having someone visit the site, take a sample and perform lab based testing in the long run.

Its a good idea, but as it's objective is measurement of biological factors rather than a direct chemical/physical measurement and the regulatory thresholds are low relative to the measurable threshold, its not something that would be immediately practical from a hazard control perspective.
(Local Authorities, engineers, designers etc. will have to consider the ongoing maintenance cost, downtime % etc. before utilizing it, the number would have to stack up against conventional lab tests that it can't replace that are required by regulation anyway (BOD etc.)

Some_randomer

Thanks for the update much appreciated. Yes I'm stating to realise how difficult it would be to test for E Coli outside a lab. I did find a piece of kit called Waspmote that has sensors for pH, oxygen, salinity and several other properties so this is similar to my second approach:


http://www.libelium.com/smart-water-sensors-to-monitor-water-quality-in-rivers-lakes-and-the-sea/


So now I'm a bit up in the air as to what to do - if it exists already that reduces the attractiveness and USP of my project so might be back to the drawing board.

Roger Hassenforder

Some_randomer wrote: »

Calling all scientists / engineers, hope I'm in the right place. I'm looking for a beach water testing kit that can monitor and test for E Coli on an ongoing basis according to the www.epa.ie spec for beach water safety. It would need to be deployed and work continuously in water (as opposed to on land). Would also need to have some kind of port / interface to retrieve the test result data.



Does anyone know if such a thing exists? All I've found so far is manual testing kits that work on land and take 48 hours or longer to produce results.

There are systems out there, for online monitoring of bugs. E.g.
http://www.colifast.no/products/

Google online E.coli montitors.

Heres a comparison of a few systems
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3126364/

These are primarily used by utilities though in process control, and are expensive.Are you talking about deploying something on a buoy at sea, with some form of GSM/SCADA?

The_Captain

What you're looking for is effectively impossible.

You could technically run a sample through a MALDI-TOF MS and get near instant results, but that's subject to all the usual limitations of DNA detection.

While you could test for salinity/nitrogen level changes etc, none of that is a definite sign of the presence of E.Coli, and your results will be all over the place if measuring then and there in seawater. There's just too much variation to give any kind of accuracy to readings.

Then of course, I don't think you appreciate the amount of unseen work that goes with testing. You'll need to develop a methodology, go through product testing, run the machine against controls, get the methodology accredited and have your methods constantly audited to have some sort of legal framework around the results you're putting out.

Capt'n Midnight

since the e coli will be coming mainly from rivers you could sample them instead of the sea

Roger Hassenforder

Capt'n Midnight wrote: »

since the e coli will be coming mainly from rivers you could sample them instead of the sea

Streams have usually much higher levels of bacteria, usually have "no bathing" signs by them.

Capt'n Midnight

Roger Hassenforder wrote: »

Streams have usually much higher levels of bacteria, usually have "no bathing" signs by them.

easier to count

might be a good predictor of what's on the beach later on

Some_randomer

Roger Hassenforder wrote: »

Are you talking about deploying something on a buoy at sea, with some form of GSM/SCADA?

Yes that was the idea, something that could send data back from a remote "testing kit".

The_Captain wrote: »

What you're looking for is effectively impossible.

So you're saying there's a chance

Roger Hassenforder

Some_randomer wrote: »

Yes that was the idea, something that could send data back from a remote "testing kit".

They exist, but in a marine environment, they'd last about a week