ADVOCACY: Septic Tank health check

Septic Tanks are an ongoing health and safety concern in the living environment.

How long since your septic system has had a health check?

Diagram based off Ri-industries ATSIC coverslab specification. Importantly the diagram shows the lid has inspection openings at crucial points of the system for easy inspection and maintenance and the lid (rated for lightweight vehicles) rests on the ground spreading load, not directly on the tank. 

Overview

Septic tanks are common wastewater treatment solutions in remote communities we work in, data shows they are used in 41% of surveyed houses.

A septic system has the important job of catching, processing and treating all the wastewater that comes from a house – from the floor wastes, washing machine, shower, kitchen & laundry sink, basin and toilet.

Leaking taps, running toilet cisterns and crowding increase the amount of water entering the septic system reducing the treatment time (often 3 days) and capacity of the system, often causing it to overflow into the yard with raw sewage or waste not properly treated passed through the system. This can be addressed with cyclical maintenance.

SA Housing are notable to mentioned as they specify and maintain well-designed Septic Systems in remote communities. They consider cover slab design/installation, Septic tank installation, regular checks and work to achieve pumping out approximately every 2 years (read more below).

See maintenance recommendations outlined in The Guide and a great video created in 2011 explaining how a Septic Tank works for the Nepal Village Sanitation Project.

Detailed and technical information on the topic

Issues/ concerns with Septic Tanks & lids –

As well as the detailed information outlined in The Guide; 

• The design of the gatic lid (heavy metal lid in the concrete cover slab lid) often sits in a metal rim. If groundwater gets exposed to this ie. water from a hose or leaking yard tap, the salts in the hard water corrode the metal and make it very hard to open the lid for inspections and maintenance (including pumping out the septic tank). This is especially the case if the gatic lid is not regularly opened
• Septic tanks and soakage trenches are very susceptible to damage from vehicles and mowers etc, hence robust and well-placed ‘bollards’, fences and mounds are important to protect the system OR lids which are trafficable for light vehicles
• Small Inspection Openings (IO’s) required for maintenance checks can become covered and lose the lids that cover the opening. Grass, rubbish and objects can enter and block the system

Septic Tank lids – ATSIC lid with inspection openings (IO) vs. a real life application with no IO’s

Maintenance Recommendations –

As well as the maintenance recommendations outlined in The Guide; 

• Check for and fix any household leaks eg. leaking kitchen tap, to ensure the septic tank can work at full capacity
• Regular checks should measure sludge and crust levels to determine the working capacity of the septic tank. The more sludge and crust that is built up, the less capacity (volume) the septic tank has to process and treat the wastewater coming from the house, eg. a 3000L septic tank may only be processing a 1000L of wastewater
• Septic tanks should be pumped out regularly – SA Housing in response to state health requirements, pumps out tanks every two years

Cyclical Maintenance recommendations excerpt as outlined in The Guide

Important specifications & information shared with us from SA Housing

• Cover slab must be engineered to withstand light traffic (cars and light 4wd) and spreads loads by resting on the ground around the tank, not directly on the septic tank shell
• The cover slab must not come into contact with the saddle riser, and must use a compression foam gasket or equivalent
• Septic tank must be backfilled around the unit and compacted at installation
• All old septic tanks must be formally decommissioned – crushed, backfilled and compacted
• Engineered reinforcement must be a part of the cover slab construction
• Regular checks and pumping out is important, approximately every 2 years is advised

Further resources and references –

• Nganampa Health – ‘Septic Tank Maintenance Guide’
• SA Health – ‘Wastewater Fact Sheet’
• Healthabitat – ‘How a septic tank works’ (based on work in Nepal)
• NT Government – ‘Check and pump out your septic tank’

The housing for health methodology employs trades to carry out an independent audit of all septic tanks found in community housing on projects. The data collected and recommendations by trades inform what safety upgrades or maintenance works are carried out.