My JoJo Tank Water Smells Bad - Is It Safe to Drink? (2026)

Quick answer

A faint earthy smell is usually harmless algae. A rotten-egg (sulphur) smell means anaerobic bacteria - don't drink it without treatment. A plastic/chemical smell from a new tank fades in 2-3 fills.

Why your tank smells

• Sunlight on a translucent tank = algae bloom. JoJo's dark green tanks block 99% of light; lighter tanks need a shade cover.
• No first-flush diverter = bird droppings and roof dust enter on the first 20L of every rainfall.
• Stagnation = water sitting >3 months without turnover, especially in summer.
• Cracked inlet screen = mosquito larvae and frogs.

How to clean a JoJo tank (the right way)

1. Drain to about 100mm and scrub the inside walls with a long brush. No detergents.
2. Refill to 1,000L.
3. Add household bleach (unscented, 3.5% sodium hypochlorite) at 40ml per 1,000L for drinking water. For shock disinfection use 200ml per 1,000L, then flush.
4. Open every tap until you smell chlorine, then leave for 24 hours.
5. Drain to garden, refill.

When to NOT drink it

• Visible green slime or biofilm = shock chlorinate + filter before drinking
• Sulphur smell that doesn't lift after chlorination = call a water quality specialist
• Within 50m of a septic tank = test for E. coli (R350 at any SANAS lab)

Long-term fix

Fit a first-flush diverter (R450), a 5-micron sediment filter (R900), and a UV steriliser if drinking (R3,200). Find local installers in Cape Town or Durban.