The need to save water has never been more paramount than now. Local municipalities are focusing on upgrading water infrastructure systems to stem water wastage and to ensure water supplies are hygienic for communities. Commercial and residential entities are looking to use grey water wherever possible to cut back on water usage and the related costs.

Technicrete and Rocla, part of the Infrastructure Specialist Group, both offer water harvesting friendly options through permeable paving solutions and concrete water collection tank systems.

Concrete Water Tanks

Many water harvesting systems are available for water catchment and recycling, but one of the key requirements for water re-use is ‘clean and hygienic’ water storage facilities. Rocla, the South African concrete specialists, offer underground, concrete rainwater harvesting solutions in the form of their ecoRain and ecoRain Plus systems. These systems, which have been applied successfully in Australia, one of the driest regions globally, are considerably more hygienic when compared to above ground plastic alternatives where micro-organisms can grow due to warm, light conditions

The concrete tanks comprise underground precast tanks complete with manhole access chambers, a sediment filtration system, velocity reducing inlet and outlet overflow structure. Top-up systems, pumps electrical control system and safety switch can be supplied by the installer.

Essentially the system connects to roof downpipes and captures the water for underground storage. This captured water supply can be re-used for toilet flushing, laundry and gardening activities. It is relatively easy to install, maintain, is durable and requires little maintenance.

Manna Hoogenboezem from Use-Rainwater, who partners with Rocla on the concrete tank solutions, said “At the moment, in South Africa the Rocla option is mainly being utilised by commercial applications and in selected residential applications where the customer requires a long-term, good quality investment”.

“This modular concept is a pre-manufactured tank that can be commissioned and installed within a few days with minimal interruption at site. While plastic will always be cheaper, a major benefit offered by the concrete tank is that the lime in the tank naturally neutralizes the slight acidity of water – with a plastic tank you have to manage the water alkalinity, this is not required with the concrete tank. This is an issue that water harvesting users need to be educated on” said Hoogenboezem.

Other benefits of the Rocla concrete tank are that concrete allows for minimal fluctuations in water storage temperature, which is ideal for captured rainwater, which requires a cool and dark environment for natural removal of most micro-organisms. Plastic has a limited lifespan whereas the concrete tank, if managed correctly, lasts a lifetime.

Hoogenboezem said “Use-Rainwater specialises in the design of rainwater harvesting systems. We support and promote the Rocla concrete tank concept as it is compatible with many of our own solutions. We are currently preparing final layouts for installation of a concrete tank system in a residential dwelling in Pretoria. It will be installed in the basement and will be used for potable rainwater harvesting, as well as a back-up water system should the municipal supply be interrupted. If one thinks about the water hygiene coupled with the storage and recycling capabilities, the Rocla tank is the way forward” he said.

Permeable Paving

Hard landscaped paved walk-and-driveways in industrial and residential developments are often the first areas under water when heavy rains fall and the storm water discharge management system is inadequate. Imagine being able to easily remove AND harvest this water supply in an environmentally friendly way at source. This water can be recycled as gray water for non-potable or irrigation use. Sustainable Urban Drainage Systems offer precisely such opportunities.

SUDS are used to prevent and alleviate flooding and unwanted water run-off in areas that have of necessity hardscaped heavy-duty applications such as car parks, industrial estates, domestic drives, airport service areas and such like. The Technicrete   Aquaflow permeable paving allows heavy rain to infiltrate through a permeable concrete block pavement via special slots in the concrete paving blocks, into a special sub-base consisting of stone, where the storm water is then  retained in the stone matrix. The water is then ready for re-use or for controlled release into sewers or gray water supplies, thereby eliminating excessive pressure on existing storm water systems.

Heavy metals, hydrocarbons, rubber, dust, silts and other debris which are generally deposited on impermeable surfaces during dry weather, are removed to treatment works, rivers or streams during rainfalls causing severe environmental damage and severe secondary pollution. Technicrete’s Aquaflow permeable paving  offers two unique solutions – superior water harvesting and environmental protection.

Technicrete’s Aquaflow permeable paving not only requires less space because of more efficient land use, it is also a more cost effective solution, with the permeable paving offering instant pollution control at source. Analysis of water exiting from the Aquaflow system has been found to be as clean as water from a  modern sewage works and with a pH of approximately 7.5, it makes sense to utilise these unique SUDS philosophies and paving techniques in local water harvesting operations. To date youth hostels and schools are using water passed through and filtered by this system for non-potable purposes as lavatory flushing while garden centres are using the technique to water plants and soft landscaped areas, where it has been found that the  Aquaflow system is kinder to plants than ordinary tap water.

The most popular usage of these systems is for storm-water attenuation under large parking areas, thereby reducing damage to natural waterways from rapidly flowing water.

There are three basic designs available: a typical infiltration system, atypical attenuation system with controlled reduced discharge into the existing storm water management system, and a typical water attenuation and harvesting system, each of which can be tailored to the customer’s requirements.