Domestic Water Treatment Frequently Asked Questions
How does my sceptic tank work?
Septic Tanks work by taking effluent from the house by pipe to the septic tank.
This tank normally has two chambers where solids settle and liquid effluent floats
to the surface. It is this liquified effluent that flows to your percolation area
which under normal circumstances percolates down through the soil and is treated
In areas where there is poor soil drainage (approx 25% of the country), this
type of system does not work properly as the soil is not capable of allowing
the necessary percolation for effective treatment of effluent. Luckily, this
type of soil (poorly drained) is perfect for use in ICWs.
If you think you have a suitable site and would like to find out more, please
contact us for a free consultation.
How do I know that my septic tank isn’t working properly?
When your septic tank isn’t working, there may be all or some of the following symptoms:
- An unpleasant smell from the area surrounding the septic tank
- Ponding of effluent around the septic tank
- Lush, green vegetation or grass around the percolation area.
- Backing up of effluent and odours coming from toilets & sinks.
What is the effect on the environment and my
water supply if my septic tanks isn't working?
If your septic tank isn’t working, effluent either flows over the surface to
adjacent ditches or drains (and eventually to the watercourse) or it goes
directly into the groundwater.
Groundwater is a living body of water that is connected surface water (drains and
ditches) and also to local wells that supply us with drinking water. If you use
a well for drinking water your septic tank effluent could be polluting this source.
Likewise, if your effluent is flowing to a drain or ditch, this source flows to
streams and rivers that provide drinking water to group water schemes and
municipal water supplies.
The diagram above shows that the proximity of your septic tank to a well or
drain could be polluting the water that you drink every day.
This type of pollution is also very harmful to the environment
upon which flora and fauna depend on to survive.
How does an ICW work?
“Integrated Constructed Wetlands” (ICWs) work using a series of shallow ponds
(typically 3-4 in series), connected by pipework and densely planted with a mix
of wetland vegetation. This vegetation includes reeds, rushes, irises and sedges.
Effluent flows (generally by gravity) from the septic tank to the first pond and subsequently to the other ponds.
ICWs have been proven to remove over 99% of all pollutants from domestic effluent.
Effluent is treated in a number of ways:
- Microbial action. Effluent moves at a very slow pace within the ICW system and as a result, biofilms form on the surface of plant roots, allowing a microbial population to grow and feed on pollution within the system.
- Dense planting slows down the flow of effluent, allowing microbial breakdown while also allowing any particals to settle down to the base of the ponds.
- Leaf litter (necromass) from the vegetation deposits on the base of the ponds over time, creating an environment where anaerobic digestion and other processes can take place.
Are ICWs approved systems in Ireland?
Yes. Integrated Constructed Wetlands are approved as a suitable solution to household septic tank effluent treatment.
A guidance document was published by the Department of Environment, Heritage and Local Government in 2010 giving full guidelines on Integrated Constructed Wetlands.
Read our Integrated Constructed Wetlands Guidance Document for Farmyard Soiled Water and Domestic Wastewater Applications.
The EPA also make reference to Constructed Wetlands as an approved system in their guidance documents for Single Houses.
How do I know if my site is suitable for an ICW?
The design of Integrated Constructed Wetlands (ICWs) are entirely site specific as there is a huge variation within the country of soil types, climate and topography.
However, if your site has any or all of the following characteristics, it may be suitable for the construction of a wetland.
- Poor drainage. This may be represented by ponding or the presence of rushes and other wetland vegetation.
- An extremely fast percolation rate. If you live in an area of karst characteristics
(e.g. The Burren), you may have very shallow soils with the bedrock only a foot or so below the surface.
This would mean that there is insufficient soil to act as treatment for a typical percolation area and could mean
that sewage effluent is flowing directly into the groundwater, potentially polluting the drinking water.
Typical site with vegetation suggesting poor drainage & ponding of effluent around a percolation area.
Vesi Environmental offers you a free consultation to assess whether your site is suitable for an ICW.
Please contact us for further details on suitability
Can I use my existing septic tank?
Yes. Integrated Constructed Wetlands (ICWs) can be fitted either to a new septic tank or they can also be retrofitted to an existing septic tank.
See diagram below showing how an ICW compares with a standard septic tank and percolation area.
As can be seen, an ICW takes up the equivalent of 2 typical percolation areas, side by side.
What is the ICW design and build process?
Vesi Environmental have over 15 years experience in the design, planning, construction and
maintenance of Integrated Constructed Wetlands.(ICWs)
Step 1: Initial Site Assessment
Vesi Environmental can carry out and initial site assessment using ordinance and
geological survey data in order to give a general picture of the site properties.
If you would like Vesi Environmental to carry out an initial survey free of charge
on your site, please contact us.
Step 2: Site Visit
A site visit is carried out to obtain information about soil, local vegetation,
topography and climatic conditions. Soil samples are taken and tested to ensure
the permeability of the soil is sufficient to form the clay liner that is placed
at the base of the ponds during construction.
Step 3: Approval
Vesi Environmental would generally encourage people to contact their local authority
for approval, prior to the decision to install an ICW. Vesi Environmental have a
working relationship with many local authorities and are available to liaise with
the relevant Environment or Water Services Department.
If you are building a new house, the ICW can be submitted as part of the planning application.
Step 4: Design
Vesi Environmental will draw up the relevant plans, setions and images using Autocad
according to the Department of Environment, Heritage & Local Government Guidelines
and submit them to you for approval.
Step 5: Construction
Once agreement has been reached with client and local authority, construction can
begin on site. Vesi Environmental will organise all plant hire and equipment
necessary for construction.
Step 6: Planting
Vesi Environmental have a dedicated wetland species nursery that supply plants
for the vegetation stage of the ICW. All ponds are densely planted with a mix
of sedges, rushes, reeds and wildflowers. At this stage, any additional
landscape works that have been agreed will be carried out.
Step 7: Aftercare
Vesi Environmental will draw up a specific maintenance plan for your site.
This will include all checks that should be made in a simple to follow proceedure.
How does an ICW compare with a "Reed Bed"?
A “Reedbed” is a general term that is used to describe constructed wetlands in Ireland.
In fact a Reed Bed is a different system, generally smaller and gravel based with a
monoculture of reeds. This means that the biodiversity value is diminished and the
water treatment efficiency is limited. A reedbed is generally a lined, gravel filled
container that is used in conjuction with another treatment system as a polishing
filter for effluent.
An Integrated Constructed Wetland can be used in conjunction with an existing septic tank
and does not require an additional treatment system.
A constructed wetland is a natural clay lined system (using on site soils) planted with mix of
wetland plants (including Reeds) and provide more of a natural habitat that supports
wildlife and increases biodiversity.
There are two main types of constructed wetland
- Surface Flow Wetland: Effluent flows over the surface of the pond interacting with the plants and sediment within the system to remove effluent.
- Sub-surface Flow Wetland: Effluent flows through a substrate (generally gravel) and is treated by sedimentation within the substrate.
A reedbed is generally a lined, gravel filled container that is used in conjuction with another treatment system as a polishing filter for effluent.
An Integrated Constructed Wetland can be used in conjunction with an existing septic tank and does not require an additional treatment system.
An Integrated Constructed Wetland is a type of Surface Flow Wetland and is planted with a mix of wetland plants
(including reeds) which provides a more natural habitat that supports wildlife and increases biodiversity.
What is the cost of an Integrated Constructed Wetland?
Every site that we deal with is site specific,
therefore costs depend on available materials, site conditions, size etc.
However on average a system install would be comparable to packaged treatment
systems that may be installed in new single houses but with the advantage of
very little maintenance involved.
Please contact us to discuss ICW costs
Do Integrated Constructed Wetlands need to be fenced off?
ICWs are designed to have shallow water depths (100-300mm) and shallow sloping banks (1:2) which means there are a safe system to have within the garden.
The first pond is generally where there may be any odour and as a result, ICWs are designed so that this first pond is placed the furthest away from the house.
If there is still a concern, this first pond can be fenced off with the other ponds being left open.
Alternatively the entire system may be fenced off but in general, due to the dense vegetation and the shallow water depths, fencing is deemed unnecessary.
What kind of maintenance is involved with a domestic ICW?
A fundamental aspect of the ICW concept is that the wetlands are designed as self manageable
and self maintaining as possible. There are however a few simples checks that must to done to maintain this robustness. This includes checking pipes, water levels and sediment levels.
A comprehensive maintenance schedule is created once the ICW has been completed.