Vertical Tank Installation: The Complete Professional Guidelines

1. General Installation & Site Preparation

Vertical tanks must always be installed in an upright position on a solid, level surface, with the entire base fully supported to ensure long-term stability. The installation area must be cleared of all rocks, sharp edges, iron bars, or debris that could damage the tank during use or cause uneven settling over time.

The prepared base should extend well beyond the outer diameter of the tank to allow for safe load distribution and prevent edge deformation. Suitable foundation materials include bricks, reinforced concrete pads, or a properly compacted gravel base topped with a 300 to 400 mm deep sand layer.

Allow a minimum clearance of 150 mm between the tank and any surrounding structures or walls to accommodate expansion as the tank fills and empties, and to ensure easy access for cleaning and maintenance.

When positioning the tank, consider optimal orientation for both filling and maintenance access, and ensure safety around the tank during operation. If the tank is being installed in an exposed or windy location, particularly when empty, it should be securely strapped or anchored to prevent tipping or movement.

Tanks should not be installed underground unless specifically engineered for such applications. Vertical storage tanks are designed for static installations only and should not be used in transport scenarios.

2. Base Foundations & Support

A reinforced concrete pad is always the preferred option for providing long-term stability and preventing uneven settlement or subsidence. For smaller tanks, typically up to 1000 L, a well-compacted sand or gravel bed may be acceptable if wind loading is not expected to be an issue.

For tanks in the 2000 L to 15,000 L range, a reinforced concrete base is mandatory to safely handle the static load, especially when full.

Steel support stands must be designed and certified by a qualified engineer and must be securely mounted on a reinforced concrete base of appropriate size and depth to support both the tank weight and any dynamic forces from wind or site activity. The stands should be securely bolted to the foundation to resist vibration, accidental impact, or shifting.

Platform surfaces must not have gaps wider than 50 mm, as wider spacing may create stress points on the tank base and risk distortion or damage under load. The tank base must be fully and evenly supported across its entire footprint — point loading or uneven supports are not acceptable under any circumstances.

3. Handling & Delivery Inspection

It is essential to inspect each tank thoroughly upon delivery. Any visible damage or manufacturing defects should be documented immediately and noted on the driver’s delivery note to protect warranty rights.

Handle tanks with care during unloading. They should never be dragged or rolled over fittings, nor across abrasive or sharp surfaces. Avoid forklift blade damage by using padded forks if mechanical handling is required.

Ensure the unloading area is clear of hazards such as sharp stones, debris, or protrusions that could compromise the tank.

Tanks should always be moved while empty and transported with care to avoid deformation. Never climb, sit, or stand on the tank at any stage, as the surfaces may be slippery, especially when wet, posing a serious risk of injury. Damage to the tank structure or fittings may also occur if improper handling practices are used.

4. Pipework & Fittings Installation

Pipework and fittings connected to the tank must always be independently supported to prevent loading stresses from being transferred onto the tank body or fittings.

Flexible pipe sections must be installed between the tank and any rigid piping to absorb movement caused by thermal expansion, vibrations, or minor settlement. Improperly supported or rigid pipework can place excessive stress on fittings, leading to leaks or long-term deformation of the tank wall.

For rectangular tanks, if the tank height exceeds 500 mm, the side walls must be adequately supported to maintain structural integrity under liquid load.

Heavy equipment, valves, or meters must never be mounted directly on the tank or unsupported fittings, as this may result in stress fractures. Use expansion joints where required to allow for differential movement between tank and pipework.

Plastic bulkhead fittings should be tightened by hand only. Over-tightening with tools can cause cracking or permanent distortion. Likewise, hard metal or steel fittings must never be forced onto plastic threads, as this risks thread stripping or fitting damage.

Following installation, the tank should be filled with water and held for a minimum of 5 hours to test for leaks and verify proper seating of all fittings.

5. Usage Limitations & Operating Conditions

Vertical tanks are intended for atmospheric storage applications only and are not designed to operate under vacuum or pressure conditions.

When installing immersion heaters, ensure they are positioned with at least 75 to 100 mm clearance from the tank wall to avoid localised overheating or structural deformation of the tank body.

The maximum recommended temperature for stored liquids is 50°C. Exposure to higher temperatures may soften or weaken the tank material, reducing service life.

Tanks should be protected from impact, particularly when ambient temperatures fall below 4°C, as the material may become brittle and more prone to cracking.

The interior of the tank constitutes a confined space and should only be entered with appropriate safety procedures in place. Follow confined space entry regulations and best practice at all times.

Tank capacity will naturally vary with temperature fluctuations, the specific gravity of the contents, and tank wall flexibility. Some variation in measured volume is normal and should be allowed for in operations.

6. Professional Guidelines for Septic Tank Installation

6.1. Pre-Installation Planning

Tank size: The required volume depends on household wastewater production and how often the tank will be emptied. As a general guide, hand and face washing uses 1–4 litres, toilet flushing 3–7 litres, a bath 50–150 litres, a five-minute shower about 80 litres, and a 5 kg load of laundry approximately 80 litres. These figures provide a rough basis for estimating daily demand.

Professional assistance: Because of the complexity of septic and conservancy systems, installation should be undertaken by or under the guidance of a qualified contractor. A complete system requires not only the tank itself but also access to licensed pumping services for periodic emptying.

Tank placement: Choose a location with a soil bearing capacity of at least 120 kPa. Avoid areas prone to flooding, saturated clay soils, or where the bedrock lies closer than 2.5 metres to the surface. The tank should also not be placed under vehicle routes or in areas where underground services such as cables, water pipes, or gas lines are expected.

6.2. Excavation and Bedding

Excavation depth should generally be 420–720 mm below the tank's base, depending on site conditions such as groundwater and anticipated traffic. A clearance of 300–600 mm on all sides should be provided. Bedding material must be carefully selected: rocky ground requires a 150 mm layer of crusher dust or gravel, while coarse dry sand may be stabilised with a light cement mix. Fine soils such as silt or clay should be compacted in two 150 mm layers, also stabilised with cement. All loose stones and debris should be removed, the bedding spread evenly, and compacted mechanically. Natural soil moisture is generally sufficient for cement curing, and excess water should not be added.

6.3. Tank Placement and Inlet Connection

Once the base is prepared, the tank is carefully lowered into position, aligned with the intended inlet and outlet direction. A 110 mm hole is drilled at the designated inlet point, and the pipe with elbow is fitted securely. Joints should be sealed with pan connector sealer or similar compounds to ensure watertightness.

6.4. Backfilling Procedure

Backfilling must be carried out in stages to protect the tank's structure. Suitable material includes clean river sand or a sand–gravel mixture with no stones larger than 20 mm. For a 6000 L tank, the procedure is to fill the tank with 150 mm of water, then place a 150 mm layer of backfill around the sides and compact before repeating. This alternating process continues until the excavation is filled halfway. Smaller tanks, typically between 1250 L and 2500 L, should be filled completely with water before layered backfilling begins. Proper compaction is essential and may be tested by dropping a wooden handle from about 300 mm: a clear "ping" sound indicates the required density of roughly 97% Mod. AASHTO.

6.5. Lid, Plumbing and Final Backfill

After the first stage of backfilling, the tank lid should be filled with concrete, cured, and secured in place. Plumbing connections from the household, including both black and grey water feeds, are then connected to the inlet elbow. It is strongly advised that a qualified plumber completes this stage. Once complete, the remaining excavation can be backfilled, following the same compaction requirements as before.

6.6. Dressing and Load Considerations

The cover above the tank depends on site conditions. In non-load-bearing locations, 200–750 mm of soil cover is sufficient. Where vehicle traffic is expected, reinforced measures must be taken: a 450 mm concrete ballast layer across the tank footprint will prevent flotation when the tank is empty, and in high-traffic areas a reinforced 150 mm slab should be provided, extending 4.2 m by 2.9 m and designed for appropriate loading. The final surface should always be shaped to direct water away from the tank.

6.7. Access and Maintenance

It is strongly recommended that a manhole be installed above the tank to allow for easy pumping and maintenance. Arrangements with a licensed sludge-hauling company should be made in advance, ensuring prompt service when the tank reaches capacity. Routine inspection of seals, the lid, and the soil surface around the installation will help ensure long-term performance.

6. Notes on Tank Sizes & Volume

Published tank sizes are nominal and provided as industry-standard references. Moulded calibration markings on the tank are intended as visual guides only and are not calibrated to serve as precision measurement instruments.

True tank capacity can vary significantly based on several factors, including:

• The tank’s physical dimensions and wall thickness
• The specific gravity and density of the stored liquid — heavier liquids may reduce usable capacity
• The temperature of both the stored liquid and the surrounding environment, which affects tank expansion
• Daily ambient temperature cycles — polyethylene tanks will naturally expand and contract over time

For applications where exact volume measurement is critical, users should test and calibrate the tank on-site and monitor periodically to account for the expected variations in effective capacity.

7. Tank Drawings and Design Sketches