Field-Testing Water Quality Without a Lab

Field-Friendly Microbiology: A Simple Incubation Method for Detecting Clostridium as a Proxy for Cryptosporidium

One of the major challenges in treating waterborne diseases like cryptosporidiosis isn’t just the treatment itself—it’s the verification. Cryptosporidium, a resilient parasite often found in contaminated water, can be difficult to detect directly, especially in remote or resource-limited settings. In laboratory conditions, Clostridium perfringens is often used as an indicator organism due to its similar resistance to disinfection processes.

However, traditional detection methods for C. perfringens rely on anaerobic incubation at 45°C, a requirement that usually necessitates expensive laboratory equipment and facilities. This creates a significant barrier in rural settings like Zinga Island, Uganda—where distance, cost, and limited transport options make routine lab testing nearly impossible.

So, what do you do when you need lab results but have no lab?

You innovate.

Creating Anaerobic Conditions (With a Candle!)

To simulate anaerobic conditions – a must for growing Clostridium – we used a candle jar method:

• A mayonnaise jar was cleaned and repurposed.

• Petri dishes were prepared using blood agar (as the more specific Tryptose-Sulfite-Cycloserine agar was unavailable).

• The dishes were affixed to the bottom of the jar using candlewax.

• A candle was inserted, lit, and the jar was sealed.

• As the candle burned, it consumed the available oxygen, creating an anaerobic environment ideal for Clostridiumgrowth.

This simple method effectively mimics lab anaerobic chambers without the cost or complexity.

Results: Promising and Practical

After incubation:

• Lake water samples (known to contain Clostridium) produced approximately 200 bacterial colonies.

• Microscopic analysis confirmed the presence of both rods and spores characteristic of Clostridium.

• While full species identification wasn’t possible with the available microscope, the strong presence of known Clostridium in the samples makes the result highly probable.

• The procedure was then repeated using a heat-treated sample. This time, no colonies were observed, suggesting effective disinfection.

Developing a DIY Field Incubation System

We developed a low-cost, field-adaptable method for screening Clostridium in water samples. While not intended as a replacement for certified lab testing, this method offers a reliable initial screening tool—a crucial step for identifying problem areas and assessing treatment effectiveness on-site. Confirmatory samples should still be sent to accredited labs whenever possible.

An added benefit? Our solar thermal water disinfection system readily provides water heated to 40–50°C, which is close to the optimal incubation temperature for C. perfringens. This meant we could repurpose our existing setup to create a practical incubation environment.

Building a Makeshift Incubator from a Water Barrel

To maintain the necessary incubation temperature, we repurposed a 50-liter water barrel:

• The barrel was insulated with four layers of Styrofoam and one layer of silver-backed fiberglass insulation.

• It was filled with water heated to 53°C.

• The sealed jar was placed upright inside the barrel using a clever stabilizing method: an athletic sock tied to a rockto keep it vertical.

The barrel was then closed to retain heat and left undisturbed for 18 hours.

Why This Matters

This approach proves that field-friendly microbiology is possible. With a little creativity and a lot of determination, we can bridge the gap between fieldwork and science—enabling communities and student researchers to monitor water quality, even in remote settings.

And most importantly, we’re sharing this method open-source. If you’re a student, innovator, or health worker working in the field—we invite you to adapt, replicate, and improve on our technique.

Let’s make clean water not just a goal, but a shared practice.

Together, we develop water.