Decision support tool

Background information

Guideline values and regulations

For drinking-water, guideline values and standards define concentrations considered safe for a lifetime consumption of 2 litres of drinking-water per person and day.

Health authorities may allow a slight exceedance, for a short time, if no health risk is to be expected, the public is informed and a remediation plan is available ensuring that the standards are met within some years.

For exposure via bathing, higher limit values are acceptable since the potential exposure is not likely to the life-long and only about 20-50 ml of water are typically swallowed during a bathing session.

Guideline values

Regulations for drinking water

Regulations for bathing water

An extended compilation of international regulations for cyanobacteria and cyanotoxins in drinking and bathing water can be found here or in Literature – Guideline values and regulations.


The NOAEL (No Observed Adverse Effect Level) is the highest tested dose or concentration of a substance (i.e. a drug or chemical) at which no adverse effect is found in exposed test organisms.

[2] TDI

The TDI (Tolerable Daily Intake) is the amount of a chemical that can be taken in daily without a health risk (usually over a whole lifetime).