Underground tanks by Duraco
Site Selection
- When digging the trench, it is very important to ensure the tank is fixed on stable soil. When installing the Underground water tank in areas at risk of flooding, waterlogging (where soil is saturated with water), or with a high ground water table, it is advised to protect the tank from external pressure being applied to the wall of the tank which can cause severe damage.
Trench – Digging Process
- With respect to the length and width; and additional 30 cm around the tank should be digged
- The slope should be adjusted to the soil conditions. The depth of the trench is given by the vessel height and an additional of 15cm (Fig. 2)
Compaction Process
The 15cm rocksand and stone free should be compacted by hand (As per Fig. 3)
Underground Water Tank Placement
The Underground Water Tank is lowered into the pit (As per Figure 4) and aligned on the rock sand bed using a spirit level. It is advised to position the house service connection; inlet, outlet and the overflow and realigned again with the spirit level (Figure 5)
Filling of Water Tank with Water and Surrounding with Rocksand
The water tank tank should be filled at 30cm water level. The pit should be filled at 30 cm with rocksand and should be compacted by hand (Figure 6)
The process need to be repeated until the Water tank is filled and the pit is covered at the same time.
NOTE: In case the underground water tank needs to be installed with more than 300 mm of soil above its top, it must be protected by a heavy duty concrete slab, without resting on the underground water tank. The slab must rest on firm soil around the tank.
NOTE: Non-Compliance of above instructions voids all warranty claims.
Plumbing
Your tank should be installed by a qualified plumber in accordance with regulations, ensuring piping and fittings are correctly done to avoid any non compliance to above instructions.
What base is required to install an underground water tank?
For our underground water tank 4700L, no concrete base is required. The tank has to be placed on a 150 mm rock sand bedding.
How heavy is the tank?
The tank empty weighs 195 Kg
Is it easy to handle?
This water tank Model is equipped with ribs for easy handling.
Do you provide warranty on your tanks?
3 years warranty for underground products
Can I use an underground water tank as above ground?
Our underground water tank 4700L is designed for below ground use only. Using this tank model for above ground can result in deformation of the tank. It is far more cost-effective to utilize an above ground water tank that is specifically designed for above ground use and applications.
Is water stored in the underground water tank safe to drink?
Yes, our underground water tank is made of food grade material and can be used for drinking purposes as long as the water being supplied by the CWA satisfies the safe water drinking standard.
Can I bury the tank at 50 cm below the ground level?
No, the tank can only be buried 30 cm below ground level. In case it cannot be avoided to bury the tank more than 30 cm, the tank MUST be protected by a reinforced concrete slab that rest on firm ground around the tank. Just verify the tank is NOT supporting the load of the concrete slab.
A riser will then be adapted at the tank manhole to reach ground level.
Can I install an underground water tank under a driveway?
No, installing the water tank under a driveway is not permitted and will void the warranty.
In case it is located under the driveway, or in the pathway of heavy vehicles, the tank MUST be protected by a reinforced concrete slab that rest on firm ground around the tank. Just verify the tank is NOT supporting the load of the concrete slab.
A riser will then be adapted at the tank manhole to reach ground level.
Is there a sand/gravel mixture recommended for bedding/backfill?
No, only compacted rock sand is recommended. Use of other materials will void warranty
Why is it recommended to fill the tank with water as the soil is being backfilled while burying the tank.
Filling the tank with water while backfilling equalizes the pressure between the outside and the inside of the tank thus minimizing any possible distortion or movement of the tank.
How do you access an underground water tank?
Remove the manhole cover and access the tank (ensure that the manhole cover is always visible). In case the manhole cover does not reach ground level, a riser will then be adapted at the tank manhole