What Are MIB and Geosmin in Drinking Water?

Musty or earthy tasting drinking water is commonly caused by two naturally occurring compounds: MIB (2-Methylisoborneol) and Geosmin.

These compounds are produced by certain cyanobacteria (blue-green algae) and bacteria found in lakes, reservoirs, and rivers. They are particularly associated with algal bloom events.

While MIB and Geosmin do not pose a health risk, humans can detect them at extremely low concentrations — sometimes as little as 5–10 nanograms per litre. To put this into perspective, that is equivalent to detecting a few drops in an Olympic swimming pool. Because of this sensitivity, even very small amounts can lead to noticeable taste and odour issues in drinking water supplies, often triggering complaints from communities.

Why Monitoring Is Important

For water utilities, monitoring MIB and Geosmin is essential for managing taste and odour events. Testing allows operators to:

• Identify potential issues early

• Monitor seasonal changes in source water

• Optimise treatment processes

• Reduce consumer complaints

How MIB and Geosmin Are Removed

Treatment strategies often include:

• Powdered Activated Carbon (PAC) dosing

• Granular Activated Carbon (GAC) filtration

• Ozonation and advanced oxidation processes

  
  

Laboratory analysis, typically using GC-MS techniques, allows these compounds to be detected at extremely low concentrations.

Supporting Water Treatment Decisions

At Research Laboratory Services, we provide specialist analytical testing to help utilities understand taste and odour compounds in their water systems. Reliable monitoring data supports better treatment decisions and helps maintain confidence in drinking water quality.

In addition to MIB and Geosmin analysis, we can also support treatment optimisation through laboratory studies, including powdered activated carbon (PAC) and granular activated carbon (GAC) performance testing, as well as ozone demand assessments. These studies help utilities evaluate treatment effectiveness, optimise dosing strategies, and better manage taste and odour events during algal bloom periods.