Odaiba Marine Park Water Test Results Published

The Tokyo Organising Committee of the Olympic and Paralympic Games (Tokyo 2020) and the Tokyo Metropolitan Government (TMG) today announced that the results of water quality and temperature surveys conducted at Odaiba Marine Park demonstrate the effectiveness of the measures they have taken to secure water quality for Olympic and Paralympic competitions.

A series of experiments were conducted at Odaiba Marine Park, the venue for the Tokyo 2020 Marathon Swimming and Triathlon events, involving the installation of single- and triple-layer underwater screens; the triple-layer screens were shown to reduce the quantity of coliforms to well within targeted levels. When using triple screens, test results inside the screened areas were all within the agreed limits, even though outside of the screened area the results exceeded the targeted levels set by the corresponding international federations for 12 days due to various factors, including a typhoon which struck the area during the test period.

The surveys were conducted on days that corresponded to the scheduled dates of the Tokyo 2020 Olympic Games and Paralympic Games, and during those periods there were no instances where the targeted maximum water temperature of 31.0C was exceeded in any of the measured areas in the field of play, despite the record hot weather. The maximum temperature recorded was 30.0C and the average temperature was 27.6C. The water temperature inside the screens was on average approx. 1C higher than the temperature outside.

Based on the results of the water surveys, Tokyo 2020 and TMG will consider the deployment of underwater screens during the Tokyo 2020 Games, and will continue to make all possible preparations to ensure that all athletes can perform at their best.

2018 Survey Details

1.Survey period: (mirroring the planned dates of the relevant Olympic & Paralympic events in 2020):

  • Olympic period: July 24 to August 9
  • Paralympic period: August 25 to September 6 (underwater screen experiment during Paralympic period August 25-31)
  • the survey was not conducted on a number of days due to a typhoon

2. Survey location: Odaiba Marine Park

3. Implementing entity:

  • Water quality survey in the field of play: TMG Bureau of Olympic and Paralympic Games Tokyo 2020 Preparation, and Tokyo 2020 (28days)
  • Underwater screens experiment: TMG Bureau of Ports and Harbours (22days)

4. Measurements:

  • For Marathon Swimming: the quantity of faecal coliforms; the presence of oil film; the level of COD (Chemical Oxygen Demand); water transparency; water temperature
  • For Triathlon: the quantity of escherichia coli and enterococci bacteria; pH levels; water temperature

5. Sampling locations:

(Download a file)The result of water quality surveys (PDF: 79.2 KB)

Summary of Survey Results

The quantity of coliforms outside the screened area exceeded the targeted quantity levels set by the corresponding international federations for 12 days due to various factors, including a typhoon which struck the area during the test period. When using triple screens, test results inside the screened areas were all within the agreed limits.

Reference: Target water quality & temperature levels for specific sports Marathon Swimming: FINA water quality and temperature standards

Item Target Levels Agreed for Marathon Swimming
Quantity of faecal coliforms 1,000 or less per 100ml
Oil film Not present
COD (Chemical Oxygen Demand) 8mg or less per litre
Water transparency 0.5m or above
Water temperature 31C or less at a depth of 40cm

FINA rules stipulate that the standards set by appropriate local hygiene organisations or safety agencies in each country are acceptable measures for the certification of water quality.
Accordingly, Tokyo 2020 uses the water quality standards determined by Japan's Ministry of the Environment as indicators, and these were the standards used in these tests.

Rules governing water quality for open water swimming are published by the International Swimming Federation (FINA) on their website at
FINA website(Open in a new window)

Triathlon: ITU water quality and temperature standards

Item Target Levels Agreed for Triathlon
Quantity of escherichia coli 250 or less per 100ml
Quantity of enterococci 100 or less per 100ml
pH 6~9
Water temperature 32C or less at a depth of 60cm

Rules governing water quality for Triathlon events are published by the International Triathlon Union on their website at
ITU website(Open in a new window)

Overall results of water temperature survey

During the dates corresponding to the planned Olympic and Paralympic event dates, there were no instances where the targeted maximum water temperature of 31.0C was exceeded in any of the measured areas in the field of play. The maximum temperature recorded was 30.0C and the average temperature was 27.6C.
The water temperature inside the screens was on average 1C (and 3.8C maximum) higher than the temperature outside the screens.

Future Measures

The measures to ensure good water quality in advance of the Tokyo 2020 Games:

TMG and Tokyo 2020 will consider the deployment of underwater screens during the Tokyo 2020 Games, as these were confirmed during the survey to reduce the quantity of faecal coliforms. They will also discuss other measures, including the opening and closing of the screens in order to regulate water temperature and the quantity of pH and COD.

Underwater screens(©Tokyo Metropolitan Government)