What is a TVC?

TVC stands for Total Viable Count. It tells you how many bacteria are in the water. It is a general check of how clean the water system is.

How to Take the Sample

1. Use a clean 500ml or 1 litre bottle (with sodium thiosulphate if the water is chlorinated).
2. Remove any attachments from the tap (aerators, shower heads).
3. Do NOT clean the tap - you want to see the real condition.
4. Run the water for 2-3 seconds only (do NOT flush for a long time).
5. Fill the bottle without touching the tap.
6. Label it with date, time, location, and tap name.
7. Keep at 2-8 degrees C in a cool box.
8. Get it to the lab within 24 hours.

What the Results Mean

The lab grows the bacteria at two temperatures:

At 22 degrees C (bugs from the environment)

| Result | Meaning | |---|---| | Under 100 CFU/ml | Good | | 100-1,000 CFU/ml | Check the system | | Over 1,000 CFU/ml | Bad - investigate and fix |

At 37 degrees C (bugs from people/animals)

| Result | Meaning | |---|---| | Under 10 CFU/ml | Good | | 10-100 CFU/ml | Check the system | | Over 100 CFU/ml | Bad - investigate and fix |

What to Do If Results Are Bad

1. Look for where the bacteria are coming from.
2. Check temperatures are right.
3. Clean and disinfect if needed.
4. Test again 2-7 days after fixing.
5. If still bad, do a full investigation.