Testing
Simple ways to track what your bed is doing — and where simple testing ends.
None of these tests can confirm water is safe to drink. They tell you whether the bed is functioning. Drinking-water safety needs a verified disinfection step. Get help →
Visual indicators
Free, immediate, surprisingly useful. Compare inflow and outflow each visit.
- Smell. Earthy or neutral is normal. Sour or sewage-like means anaerobic conditions or overload — add dry material and reduce flow.
- Clarity. Hold a clear glass of inflow next to outflow. Outflow should usually be clearer.
- Sludge. Some accumulation at the inflow end is normal. Heavy sludge through the whole bed means it is time to refresh the chips.
- Flow rate. Slowing flow is fine; total blockage is a problem.
Test strips and field meters
Inexpensive aquarium, pool, or garden strips and small handheld meters track trends in your bed. They are not certified for assessing drinking-water safety.
| Measurement | What it tells you |
|---|---|
| Nitrate | Oxidized nitrogen load — expect partial reduction across a healthy bed. |
| Ammonia / ammonium | Fresh organic / nitrogenous load. High outflow ammonia means overload or anaerobic conditions. |
| pH | Acid–base balance. Healthy systems usually sit between 6.5 and 8.0. |
| Turbidity (Secchi tube) | Suspended solids. Lower outflow turbidity confirms the sediment layers are working. |
| Conductivity (EC) | Total dissolved solids; useful for spotting saline or mineral inflow shifts. Does not indicate biological safety. |
One reading proves nothing; consistent trends over weeks do. None of these tests detects viruses, parasites, dissolved metals, pesticides, or pharmaceutical residues.
Microbial testing
Microbial safety cannot be judged by sight, smell, or strips. To estimate indicator bacteria like E. coli or total coliforms, you need:
- Presence/absence kits (e.g. Colilert) — colour change indicates target bacteria are present at or above a defined detection limit.
- Membrane-filtration or plate-count kits — quantitative results, but require sterile handling and stable incubation temperature.
- A local lab, clinic, NGO, or government water-testing service.
A "negative" or "absent" result is not proof of safety: it speaks to one sample at one moment, against one or two indicator organisms, and does not detect viruses, protozoan cysts, or chemical contamination.
Before / after logging
Keep a simple log so you can spot trends and notice problems early. Useful when working with local health workers or NGOs.