Sanitary inspection of beaches

A number of studies have found that bathers themselves can be a source of faecal contamination in recreational waters (NHMRC 2008). The effect is greatest at sites where:

• dilution and tidal flushing are low, for example, in shallow coastal lakes
• the number of bathers compared to the size of the site is very high
• small children swim, wade or play at the site
• there are no toilet facilities.

Leaks from toilet facilities are most likely to be a source of microbial contamination when they are:

• located in very close proximity to the swimming area (<50 metres)
• not connected to the sewer, but rely on on-site treatment
• very old and require upgrading
• present in high numbers (high flow)
• located at a very popular beach (high use).

A history of discharges, leaks or odours may also indicate that toilet facilities are more likely to be a source of contamination.

Rainwater is removed from urban environments via the stormwater system. The runoff can carry a range of natural and artificial compounds found in, or extracted from, the catchment, including:

• silt and organic or inorganic suspended particles
• sewage from overflows and leakages in the sewerage system
• animal faecal waste (for example, dog droppings)
• oils, greases and surfactants from roadways and industrial and domestic sites
• plant fertilisers, pesticides and chemicals from building sites and gardens
• litter (including rubbish, leaf litter, grass clippings and twigs).

The amount of runoff is determined by factors such as how much rain falls and how heavy it is, the geology and landscape, the number of water-resistant surfaces in a catchment, and how wet the soil is.

Stormwater drains will have the greatest impact on recreational waters when the:

• volume of stormwater is large because the catchment is large and/or the area receives high rainfall
• catchment is densely populated
• catchment's sewerage system is old and/or poorly maintained
• drains discharge close to the swimming area.

Urban runoff is usually a large volume of fast-flowing murky water that enters drains within minutes of rainfall and eventually drains into the local creeks, rivers and harbours and onto beaches.

Very high levels of bacteria have been measured in stormwater drains at Sydney's beaches. It is recommended that you avoid all contact with stormwater, including stormwater pooled on the beach. You should also avoid swimming near stormwater drains.

Sewage treatment plants (also known as wastewater treatment plants) are located near most urban centres and remove pollutants from sewage before discharging it to the environment. Discharges from sewage/wastewater treatment plants will have the greatest impact when the:

• discharge point is located close to the swimming area
• level of dilution and dispersion available in the receiving water is low
• level of treatment at the plant is low
• volume of effluent discharged is high.

Level of treatment	Treatment process
None	Sewage is not treated: raw sewage is dicharged.
Preliminary	Sewage is filtered through screens to remove large solid material.
Primary	Sewage is filtered through fine screens to remove material like paper, cotton tips and plastic. Heavier particles like sand sink to the bottom and are removed. The sewage then flows into the primary sedimentation tanks where human waste, called sludge, settles to the bottom and oils and grease float to the surface where they are collected.
Secondary	This step removes dissolved and suspended organic and inorganic solids. Bacteria are used to naturally break down the material, then particles settle to the bottom of the tank for collection.
Tertiary	This step further removes inorganic compounds, and substances such as the plant nutrients nitrogen and phosphorus.
Disinfection	This step can be added to any treatment level to inactivate disease-causing micro-organisms such as bacteria, viruses and parasites.

During wet weather, rainwater can enter the sewage system through cracks in the pipes or illegal connections from the stormwater system. If the flow in the pipe is too much for the sewer, the extra flow (a mix of stormwater and sewage) will empty from the structures designed for overflow so the sewer doesn’t back up and overflow into houses.

Sewage overflows can also occur during dry weather if mechanical and electrical parts of the sewer system, such as those at pumping stations, fail because of power outages or other problems.

Sewage overflow points are built into the system in order to reduce both discharges to habitation and the risk to human health. Sewage overflows are either directed to a waterway or enter the stormwater system and then flow to the waterway.

Sewage overflows will have the greatest impact on recreational waters when the:

• overflow point is located close to the swimming location
• sewer system is old or poorly maintained, with cracks allowing rainwater to enter the pipes until they overflow
• sewer system is operating at close to its limits due to increases in serviced population
• sewer system serves a large population.

Sewage chokes occur when sewer pipes become blocked by tree roots, oil and grease or debris. Sewage builds up behind the blockage, leading to discharge from openings in the sewer, usually at inspection points or structures built for overflows. Sewers may also leak sewage through cracks in the pipes or areas where the pipe has been damaged.

Sewer chokes and leaks will have the greatest impact on recreational waters when:

• they are located close to the swimming location
• the sewer is operating close to its limits due to increases in the serviced population
• large trees are planted near the sewer pipes.

On-site systems, such as septic tanks, will have the greatest impact on recreational waters when they are:

• incorrectly designed or located
• not maintained and/or there is a history of leaks or odours
• present in large numbers in the catchment
• close to the swimming area, particularly if soils are sandy and porous.

Wastewater re-use, such as irrigation of treated sewage effluent on grazing land or parks or outside use in residential areas where a dual reticulation system is provided, can be a source of faecal contamination in recreational waters, particularly when:

• wastewater is not treated to a high level before re-use
• the re-use area is located close to the swimming site and soils are porous or sandy
• a large volume of effluent is re-used.

Discharges from rivers and creeks can be a significant source of faecal contamination to recreational waters, particularly when:

• the volume of river/creek discharge is high because the catchment is large and/or the region receives high rainfall
• there are many sources of faecal contamination in the catchment and the level of faecal contamination in the river/creek water is high
• the river outflow is close to the swimming site.

It should be noted that, where rivers or creeks are identified as a pollution source, care is taken to ensure that sources of faecal contamination affecting the river/creek water quality are not double-counted as pollution sources also affecting the swimming site.

Where sewage/wastewater treatment plants empty into a river, the impacts of these will be greatest when:

• the level of treatment at the sewage/wastewater treatment plant is low
• there is a large population in the catchment and a large volume of effluent is discharged from the plant
• the flow in the river is low, providing little dilution of discharged effluent.

Many coastal lagoons are open to the ocean only following heavy rain. Water quality in these lagoons tends to be poor due to the low levels of tidal flushing from clean ocean waters. These lagoons rarely affect recreational waters during dry weather conditions, but they have significant effects when the entrance is forced open following heavy rainfall.

In some cases, the lagoon entrance (outlet) has been changed and the lagoon is open to the ocean for much of the time. Water quality in these lagoons tends to be higher due to tidal flushing. However, discharges can affect recreational waters during dry weather conditions as well as during wet weather conditions.

Coastal lagoons/lakes will have the greatest impact on recreational waters when:

• discharge volumes from the lagoon are high due to a large catchment area and/or the area receives high rainfall
• the outflow is located close to the swimming site
• the lagoon receives urban or agricultural runoff or discharges from the sewage system, such as sewage overflows.

Disposal of human sewage from boats can contribute to faecal contamination in recreational waters. Boats will have the greatest impact when there are:

• a large number of them near the site
• no requirements for holding-tanks or effluent treatment before disposal
• no or insufficient pump-out facilities for boats
• no on-shore toilets.

Animal faeces can affect recreational waters, particularly when:

• large numbers of aquatic birds are present at the site
• large numbers of native animals are present at the site
• domestic animals have direct access to the water
• domestic animal exercise areas are not regularly cleaned of animal faeces.