Does the pump need to be at the same level as the tank outlet?

Not necessarily, but the relationship matters. If the pump is above the tank outlet, the suction head increases and a foot valve becomes essential to maintain prime. Most domestic pressure pumps can handle a suction lift of up to around 7–8 metres, but performance drops as lift increases, so keeping the pump as close to the tank outlet level as practical is always better.

Can I use flexible hose for the connection between the tank and the pump?

Short flexible connectors are acceptable for isolating vibration between the pump and the rigid pipework, but the suction line itself should be rigid pipe. Flexible hose under suction can collapse if the wall is insufficiently thick, which restricts flow and can cause the pump to cavitate or lose prime.

How often should the pressure vessel pre-charge be checked?

Once a year is a reasonable interval for most domestic installations. The pre-charge (air pressure on the dry side of the diaphragm) can drop over time. You check it with a tyre pressure gauge on the Schrader valve on the vessel, with the pump off and delivery-side pressure released. The target is typically 0.5 bar below the pump's cut-in pressure.

What is short-cycling and why is it a problem?

Short-cycling is when the pump switches on and off very rapidly — sometimes dozens of times per hour — rather than running for sustained periods. It happens when the pressure vessel is too small, incorrectly pre-charged, or absent. Each start draws a surge of current through the motor and contactor, so short-cycling wears out electrical components far faster than normal operation and significantly shortens pump life.

Is a Certificate of Compliance (CoC) really necessary for a pump installation?

Yes. In South Africa, any new electrical connection or modification to an installation requires a CoC under SANS 10142-1, issued by a registered electrician. Without one, your home insurance may not cover damage caused by the installation, and you may face difficulties when selling the property. A legitimate installer will include the CoC as part of the job, not offer it as an optional extra.

How a Pressure Pump Is Connected to a Water Tank (and What Installers Check)

Getting water out of a tank is straightforward; getting it out at usable pressure, quietly, and without burning out the pump is a different matter. The pipework and fittings between tank and pump are what make the difference, and they are where most DIY installations go wrong. This article walks through how a pressure pump is properly connected to a water tank, and what a competent installer checks before signing off.

The Basic Layout: What the Pipework Looks Like

At its simplest, a tank-and-pump system has five elements in sequence:

The tank outlet — a bulkhead fitting near the base of the tank, sized to match the pump’s inlet requirement.
The suction line — the pipe running from the tank to the pump inlet.
The pump itself — most domestic installations use a centrifugal pressure pump or a jet pump.
A pressure vessel (accumulator tank) — a small pre-charged vessel that absorbs pressure spikes and reduces how often the pump cycles on and off.
The delivery line — running from the pump outlet into the household plumbing.

For a broader picture of how this sits within a full backup water setup, the backup water systems guide explains the options and how components relate to one another.

The Suction Line: Diameter, Length and Slope Matter

The suction line is the segment installers spend the most time on, because mistakes here cause problems that are invisible until the pump starts losing prime or cavitating.

Pipe diameter should match or exceed the pump manufacturer’s specified inlet size — typically 25 mm (¾ inch) or 32 mm (1 inch) for most domestic pumps. Undersizing the suction line starves the pump and forces it to work harder.

Pipe length and bends add friction loss. A good installer keeps the suction line as short and straight as practical. Every 90° elbow adds the equivalent of roughly a metre of extra pipe in resistance terms, so sweeping bends are preferred over sharp elbows.

Slope matters on long horizontal runs. The pipe should slope continuously downward from the tank to the pump with no high points where air can collect. Trapped air breaks the pump’s prime and causes erratic pressure delivery.

Pipe material for suction lines should be rigid — Class 6 uPVC or HDPE is common. Flexible reinforced hose is sometimes used for short connections, but it can collapse under suction if the wall is too thin.

Non-Return Valves and Foot Valves: Keeping the Prime

A centrifugal pump cannot start pumping if the suction line has drained back into the tank. Two components prevent this:

A foot valve — fitted at the tank outlet or at the bottom of a suction pipe, it is a one-way valve that holds water in the line when the pump is off. It is the more reliable option for installations where the pump is above the tank outlet level.
A non-return valve (NRV) on the pump inlet — provides a second layer of protection and is standard practice even when a foot valve is present.

Both valves need to be accessible for inspection. They are wear items that can stick open over time, especially if the water carries any sediment.

Isolation Valves: The Detail Most DIY Installs Skip

Every pump installation should have a ball valve on the suction side and another on the delivery side. These serve two purposes: they let you isolate the pump for maintenance without draining the tank or the household pipes, and they allow a pressure test of each section independently.

A third isolation valve is sometimes fitted before the pressure vessel to allow that component to be serviced separately.

If you want to understand how this fits into the broader plumbing work on a tank installation, the article on plumbing a water tank into your system covers how the tank itself is connected to household supply.

The Pressure Vessel: Small Component, Big Impact

A pressure vessel (also called an accumulator or expansion vessel) is a sealed metal cylinder containing a rubber diaphragm with pre-charged air on one side and water on the other. It is fitted on the pump outlet, typically close to the pump.

Its job is to store a small volume of pressurised water so that minor draws — a toilet flushing, a brief tap opening — can be satisfied without the pump starting. Without it, the pump cycles on and off for every small demand, which wears out the motor contactor and pressure switch far faster than continuous running would.

For domestic systems, vessels in the 2–24 litre range are common. The correct size depends on the pump’s flow rate and the pressure switch differential. An installer should set the pre-charge pressure to roughly 0.5 bar below the pump’s cut-in pressure — a step that is often skipped on rushed jobs.

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What the Electrical Side Needs

Pressure pumps must be on a dedicated circuit with appropriate overcurrent protection. In South Africa, electrical work must comply with SANS 10142-1, and the installation must be covered by a Certificate of Compliance (CoC). A reputable installer will not leave without issuing one.

Additionally:

A thermal overload or electronic motor protection relay protects the pump if it runs dry — for instance, if the tank empties.
A dry-run protection device (float switch or flow sensor) cuts power before the pump cavitates on air.
The pressure switch must be set to the pump manufacturer’s specified cut-in and cut-out pressures. Incorrect settings are a common cause of short-cycling even when the pressure vessel is correctly sized.

What Installers Check at Commissioning

A thorough commissioning process includes:

Check	Why It Matters
Suction line is fully primed before first start	Dry-starting destroys pump seals
All joints pressure-tested for leaks	Suction-side leaks cause air ingestion; delivery-side leaks cause water damage
Pressure vessel pre-charge confirmed	Incorrect pre-charge means the vessel does not buffer effectively
Cut-in and cut-out pressures verified	Prevents short-cycling and motor overheating
Dry-run protection tested	Confirms the pump will stop safely if the tank empties
CoC issued for electrical work	Legal requirement under SANS 10142-1
Flow and pressure at furthest outlet checked	Confirms the system actually delivers usable pressure throughout the house

If an installer skips the commissioning checks, the system may appear to work on the day and fail within months.

What Does This Installation Typically Cost?

Pump and pipework installations vary considerably depending on tank size, pipe runs, and whether existing plumbing needs to be modified. As a reference point, backup tank-and-pump systems in Johannesburg typically run R20,000–R40,000, with whole-house examples around R55,000. For detail on tank costs specifically, the article on JoJo tank and pump installation costs breaks down where the money goes, and what to expect on tank installation day describes how a job typically runs from arrival to sign-off.

These are Johannesburg reference points. Labour rates, materials costs, and site complexity differ across the country, so they should be treated as a rough guide only — not a quote.

Prices vary significantly by site and region, so the only reliable number is one from an installer who has seen your setup. Get up to 3 free quotes from vetted professionals and compare them side by side.

Choosing the Right Installer

The pipework and electrical work on a pressure pump installation are not difficult for a competent tradesperson, but they require attention to detail that a generalist handyman may not have. Look for:

Plumbing experience specifically with pressure systems (not just gravity-fed tanks)
Ability to issue an electrical CoC
Willingness to walk you through the commissioning checks
References from similar residential installations

A properly installed system should run quietly, deliver consistent pressure, and require nothing more than an annual check of the pressure vessel pre-charge and the valve condition. If yours is cycling rapidly, losing pressure overnight, or running continuously, the fault almost always traces back to one of the components or settings described above.