Painting of roofs involving Tank Water
The following recommendation applies when a roof is to be painted that is used for the collection of rainwater for tankage purposes – either storage or for drinking.
All products from Coolshield International Pty Ltd recommended for the painting of roofs are free from heavy metals and are intrinsically safe when used in accordance with the following procedures.
Roofs may be painted with two different types of paint – water based or solvent based. The choice of which one can be arbitrary when used with the correct paint system or the materials of the roofing construction may dictate it. In general, metal roofs are painted with a solvent-based system whereas concrete tiles and terracotta-tiled roofs are painted with a water based paint system.
Where a roof is used for collection of water for tankage purposes, all down pipes connecting the tanks to the roofs must be disconnected so that no water or other foreign materials can enter the tanks. Simply plugging the down pipes with plugs or rags is totally inadequate.
Depending on the state of condition of any existing coatings on the roof, they must be reinstated using appropriate procedures such as removal of loose or flaking paint, priming bare metal with an appropriate primer, repairing of obvious defects such as loose or missing pointing material or cracked tiles etc and a thorough wash down (preferably a high pressure wash or stiff broom) and allowed to dry.
After the recommended paints have been applied and allowed to dry in accordance with Coolshield International Pty Ltd directions the tanks must remain disconnected from the roofs.
For solvent-based paints, the tanks must remain disconnected for a period of fourteen (14) days from the application of the last coat of paint. This is to allow any solvents to evaporate and prevent any collected water from acquiring a “kerosene type taste”.
For water-based paints, two different procedures can be used:
- At least 12 mm (the old 50 points or 1⁄2 inch) of rain must fall onto the roof. It is then prudent to collect some water from the discharge of the disconnected outlet and cautiously taste the water so as ascertain whether the water is of an acceptable quality and is also free of foam. If the water appears acceptable the tank may now be reconnected to the roof. This quantity of rain must fall onto the roof irrespective of how long the roof has been painted when no rainfall has occurred.
- Alternatively, when the final coat of paint has been allowed to dry under good drying conditions for fourteen (14) days, the roof may be gently but thoroughly washed down using a hose and a soft bristle broom. When the roof has been thoroughly treated in this manner, the whole roof should again be hosed down to remove traces of washing residues. It is suggested that a sample of the final water is cautiously tested for taste and to be free of foam. If the water appears acceptable the tank may now be reconnected to the roof.
The issue of who is responsible for the reconnection of the tank to the roofing discharge is a matter for the house owner and the painting contractor to decide. This matter should be clearly stated on any written job quotation along with any other work that may be necessary to be done.
If the above procedure has not been followed and contaminated water or washings from any cleaning processes have entered the storage tank(s), the tanks may need to be emptied and cleaned prior to filling. In this event, it is a civil matter to be settled between the house owner and the painting contractor.
For complete product specifications and MSDS please get in touch.