Can I get decent shower pressure from a gravity-fed tank without a pump?

It depends on how high the tank sits above the showerhead. As a rough guide, you need roughly 5 to 10 metres of head for a passable shower, which means the tank base would need to sit well above the roof in most homes. For most Johannesburg houses, a pump is the practical answer for any outlet above ground level or where good pressure matters.

My pump is running but pressure is still weak — what should I check first?

Start with the inlet filter on the pump, which is the most common culprit after normal use. After that, check that all isolation valves in the circuit are fully open and that the tank has adequate water in it — low tank level reduces the static head available to the pump. If those checks pass, the pump may be undersized for your peak demand or the impeller may be worn.

How do I know if my backup pump is the right size for my house?

A pump should be sized to meet your household's peak simultaneous demand — typically the number of outlets that might run at once multiplied by each outlet's flow rate. A supplier or installer should do this calculation based on your specific setup. If your pump was chosen by tank size alone rather than by actual demand, it may well be undersized.

Does SANS 241 apply to water stored in a backup tank?

SANS 241 (2024 edition) sets the standard for drinking water quality in South Africa. If you are using stored tank water for drinking or cooking, it is sensible to ensure the water meets those standards, which means appropriate tank hygiene, correct materials for fittings, and testing if there is any doubt about quality. Check with a qualified water professional if you are uncertain.

Will a pressure pump fix low pressure caused by narrow pipes?

A pump raises available pressure, but it cannot fully compensate for significant friction losses caused by pipework that is too narrow or too long. If the supply pipe from the tank is undersized, the pump will work harder and still deliver disappointing results at the tap. Ideally, both the pump and the pipework should be correctly sized together.

Low Water Pressure from a Tank: Causes and Fixes

Backup water storage solves one problem — running out of water — but it can introduce another: the pressure that trickles out of your taps feels nothing like what you were used to from the municipal supply. Before you assume something is broken, it helps to understand why tank-fed systems behave differently from a pressurised municipal connection, and which specific factor is responsible in your case.

If you are still deciding what kind of backup system to install, the overview on our backup water systems page is a good starting point. For those already dealing with weak flow, read on.

Why Tank Pressure Is Different by Nature

Municipal water arrives at your boundary at a maintained line pressure — typically somewhere between 200 kPa and 400 kPa, though this varies by area and time of day. A tank sitting on the ground or on a modest stand delivers water purely through gravity, which produces far less pressure. The basic rule: every metre of vertical height between the water surface in the tank and the outlet generates roughly 9.8 kPa of pressure. A tank sitting two metres above your tap produces around 20 kPa — noticeably weak for a shower, essentially useless for a washing machine or geyser.

This is not a fault. It is physics. The question is whether your system has been designed to compensate for it.

Cause 1: The Tank Is Not High Enough

A gravity-only setup needs the tank base to sit well above the highest outlet in the house for acceptable flow. For most single-storey Johannesburg homes, a stand height of at least 1.5 to 2 metres above the highest tap is the minimum worth considering, and even then the pressure is modest. Two-storey homes fed by a ground-level tank will almost always feel weak upstairs.

Fix: If raising the tank is impractical or structurally complicated, the real answer is a pressure pump. This brings us to the next cause.

Cause 2: No Pump, or the Wrong Pump

Many homeowners install a tank and connect it to the house plumbing without a booster pump, then wonder why the shower pressure is poor. Others do install a pump but choose one that is undersized for the flow rate their household demands.

Pumps for backup water systems are sized by two figures: maximum head (the height they can push water, expressed in metres) and flow rate (litres per minute). An entry-level pump that suits a single bathroom may not cope with two bathrooms running simultaneously. If the pump is working but pressure still feels low when multiple taps are open, the pump may simply be undersized.

Our article on whether you need a pump for a water tank walks through exactly when a pump is necessary and what type suits different setups.

Fix: Install a correctly sized pressure pump if you do not have one, or replace an undersized unit. Pump costs, installed, typically run R15,000–R35,000 depending on capacity. Get at least two or three quotes and confirm the installer has sized the pump to your actual peak demand.

Cause 3: A Failing or Poorly Set Pump

If you already have a pump but pressure has dropped off gradually, the pump itself may be the problem. Common issues include:

Worn impeller — reduces maximum head and flow over time
Air lock — can occur after the tank runs dry and refills
Pressure switch set too low — the pump cuts in and out at the wrong thresholds
Clogged inlet filter — starves the pump and reduces output

Fix: Start with the simple checks: clear the inlet filter and confirm there is no air lock by bleeding the system. If the pump is more than five or six years old and performance has deteriorated noticeably, a professional assessment is worthwhile. Adjusting the pressure switch is straightforward but should be done by someone familiar with the pump model.

Sorting out pump sizing or a full backup system can feel complicated — let the suppliers do the legwork. Compare 3 free quotes — vetted installers, no obligation.

Cause 4: Restrictions in the Pipework

Even a correctly sized pump cannot compensate for pipework that is fighting against it. Common restrictions include:

Issue	Typical symptom	Fix
Pipe diameter too small	Pressure drops sharply when multiple taps open	Upsize the supply pipe from tank or pump
Long pipe runs with many bends	Gradual pressure loss across the house	Minimise bends; upsize where practical
Partially closed isolation valve	Consistently low pressure at all outlets	Fully open all valves in the circuit
Scale or sediment in older pipes	Pressure worsens slowly over months	Flush or replace affected sections
Fine-mesh filter (pre-pump) clogged	Pressure suddenly drops	Clean or replace the filter element

If your house plumbing uses 15 mm pipe throughout and you are connecting a tank system that needs to supply multiple outlets simultaneously, pressure losses in the pipework can be significant even before the water reaches a tap.

Cause 5: The Tank Itself Is Partially Blocked or Scaled

This is less common but worth checking if the system is older. The tank outlet fitting, float valve, or the pipe immediately downstream can accumulate sediment. Polyethylene tanks do not scale internally, but fittings can corrode or debris can collect at the outlet over time.

Fix: Drain the tank and inspect the outlet fitting. Replace any corroded brass fittings with appropriate alternatives. SANS 241 (2024 edition) sets out the South African standard for drinking-water quality; if you are storing water you intend to drink, the tank should be cleaned periodically and the stored water should meet those quality requirements.

Gravity vs Pressurised: Choosing the Right Approach Going Forward

If you are reassessing your whole setup rather than patching an existing problem, the fundamental choice is between a gravity-fed system and a pressurised system. Each has genuine trade-offs around cost, maintenance, and the pressure you can expect. Our comparison of gravity vs pressurised backup water covers those trade-offs in detail.

As a rough guide, complete backup tank-and-pump systems for a Johannesburg home typically cost R20,000–R40,000 for simpler configurations, rising to around R55,000 for whole-house pressurised setups. Confirm actual costs through quotes, because sizing, tank capacity, and your specific plumbing layout all affect the final figure.

If you are ready to get the pressure problem solved properly, installers in your area can quote on the right fix for your setup. Get your free quotes here — vetted installers, no obligation.

Diagnosing the Problem Systematically

Rather than guessing, work through the causes in order:

Check tank height — measure the vertical distance from the tank base to your highest outlet.
Check whether a pump is installed and running — listen for it cutting in when you open a tap.
Inspect the pump inlet filter — clean it if blocked.
Check all isolation valves — confirm they are fully open.
Test pressure at different outlets — if only one area is weak, the restriction is downstream of the pump.
If multiple outlets are equally weak, the pump, tank height, or main supply pipe is the likely culprit.

Most low-pressure problems from a backup tank come down to one of the causes above. With a clear diagnosis, the fix is usually straightforward — and in many cases it does not require replacing the entire system.