Maintenance and service of the pressure tank – what and when to check

Maintenance and service of the pressure tank – what and when to check

The pressure tank is the heart of every home water system. It works quietly, hidden in a technical room or basement, and most owners notice it only when something stops working – the pump runs continuously, water flows intermittently, or sudden moisture appears on the floor. Regular pressure tank maintenance is simple, inexpensive, and can be done by any handy DIYer without special tools. The problem is that it is rarely discussed, and most people don’t know what to check, when, or why.

In this article, we will systematically go through the entire service cycle of a pressure tank – from understanding what happens inside the tank, through regular annual checks, to less frequent but important service tasks. We will also look at differences in maintenance depending on the type of tank (with bladder, without bladder, galvanized, stainless steel), and at what warning signs indicate an upcoming problem. If you are more interested in choosing the right tank or comparing types, I recommend reading other articles in this Knowledge Center – for example, Pressure tank with bladder or without bladder – what is the difference, Galvanized vs. stainless steel pressure tank – which is better, or What pressure to set in the pressure tank and how to check it.

How a pressure tank works and why it needs maintenance

To understand what and why to check, you first need to know what happens inside the tank. A pressure tank works on a simple principle: inside is air (or nitrogen) under pressure, which compresses the water and maintains pressure even when the pump is not running. As water is drawn off, the air volume increases and the pressure drops until the pump starts again.

In tanks with a bladder (membrane), air and water are physically separated by a rubber membrane, so air does not get into the water. In older tanks without a bladder – typically galvanized – air directly contacts the water and gradually dissolves in it. This has a consequence: tanks without a bladder gradually lose their air cushion and must be refilled. In tanks with a bladder (membrane), the condition of the membrane and the air pressure in the pneumatic part are primarily monitored.

Compressed air, a rubber membrane, and a metal shell – each of these components is subject to wear. Rubber ages and cracks, air escapes through the valve or micro-cracks, and metal corrodes. Therefore, regular inspection is essential – not once every ten years, but ideally once a year, and even more frequently for some tasks.

Service schedule: what to check and how often

In practice, I most often encounter situations where the owner of a home water system has never checked the pressure tank since its installation – even after five or six years. The result? Either they have a new pump installed (because "it switched on every three seconds"), or they have a burst membrane and the tank is effectively just a passive reservoir. In fact, it is enough to follow a simple schedule:

Every 3 months (quarterly)

• Visual inspection: Check for visible signs of moisture, water droplets, or corrosion on the tank. A galvanized tank may show white, foamy deposits (hydrocorrosion), while a stainless steel tank may swell or change color at weld points in aggressive water conditions.
• Check the pressure gauge: If there is a pressure gauge on the water circuit, monitor whether the pressure fluctuations during water withdrawal match the set values (cut-in and cut-out pressure on the pressure switch). If the pressure drops sharply immediately when the tap is opened or the pump switches on every 2–3 seconds, this is the first sign of a problem with the tank.
• Listening: Yes, literally. If the pump switches on much more frequently than before, or if water from the tap "bangs" when turned on and then quickly weakens – something has changed. A healthy tank with sufficient volume will "hold" the pressure for a longer time.

Every 6 months (semi-annually)

• Check the air pressure in the pneumatic part: Using a standard tire pressure gauge (like for car tires), check the air pressure via the Schrader valve (air valve). Before measuring, it is necessary to close the water supply and drain the water from the tank. The correct air pressure should be 0.2–0.5 bar lower than the cut-in pressure of the pressure switch. For example, if the pressure switch activates at 2 bar, the air pressure should be 1.5–1.8 bar. More about setting pressure can be found in the article What pressure to set in the pressure tank and how to check it.
• Check the functionality of the safety valve: The safety valve should always be on the inlet side. Gently turn it (if it is a manual type) and check whether it is not stuck in a closed or open position. A clogged safety valve is a serious safety risk.

Once a year (comprehensive service inspection)

• Complete check of air pressure and possible topping up
• Inspection and possible replacement of the air valve (Schrader valve – the same type as on a car tire)
• Inspection of the membrane condition (if the tank has a vacuum chamber)
• Inspection of connections and seals on the inlet pipe
• Inspection and cleaning of the filter before the pump (if installed)
• Inspection of the pressure switch – testing of set values
• For tanks without a vacuum: inspection and possible topping up of air using a hand pump

Every 3–5 years

• Replacement of the membrane (rubber vacuum) in tanks with a membrane – rubber degrades, hardens, and cracks
• For older tanks without a vacuum: visual internal inspection of the condition of the galvanized or stainless steel surface (if a maintenance hatch is accessible)
• Replacement of the pressure switch, if it shows unstable switching or corrosion of contacts

Step by step: how to correctly check air pressure in a pressure tank

This is the most important regular task and also the one that people most often do incorrectly. I describe the procedure exactly as I explain it to customers during installation:

1. Turn off the pump – disconnect it from the power supply or switch off the circuit breaker. It is not enough to just stop the water pump; the pump must be without power.
2. Close the inlet valve on the tank side, if installed. I recommend always having such a valve – it makes maintenance much easier.
3. Drain the water from the tank – open the valve on the outlet side (tap, shower) and wait until the water stops flowing. The tank must be empty, otherwise the manometer will show a combined pressure of water and air and the measured value will be inaccurate.
4. Locate the air (Schrader) valve – on most tanks it is on the top (vertical tanks) or on the side. It looks exactly like a valve on bicycle or car tires. It is covered by a plastic cap, under which is a brass or galvanized valve.
5. Measure the pressure using a standard tire pressure gauge. Digital or analog – both work equally well.
6. Compare with the required value: air pressure = pressure switch cut-in pressure minus 0.2 to 0.5 bar. Example: cut-in pressure 2.5 bar → air pressure should be 2.0–2.3 bar.
7. If the pressure is low, add air using a standard foot or compressor pump. If the pressure is too high, slightly release it by pressing the pin in the middle of the valve.
8. Restore operation: open the valve, turn on the pump, and check whether the tank fills correctly and the pressure switch switches on/off at the correct values.

Be careful of one typical mistake: if you press the valve when the tank is full and water comes out – the membrane is punctured. Air and water are mixed and water has entered the pneumatic part. In this case, membrane replacement is necessary. More about this in the section below.

Differences in maintenance: galvanized vs. stainless steel tank

The type of tank significantly affects what and how you need to inspect. If you are interested in the detailed differences, read the article Galvanized vs. stainless steel pressure tank – which is better. Here we focus on the practical implications for maintenance.

Galvanized pressure tanks (without vacuum)

An older and cheaper technology. Examples include large-capacity tanks such as Galvanized pressure tank HVP 200L with 6bar water gauge or Galvanized pressure tank HVP 300L with 6bar water gauge. These tanks have direct contact between air and water, which means:

• Air gradually absorbs into the water – a galvanized tank without a vacuum will lose its air cushion within several weeks to months, depending on the intensity of operation. It needs to be regularly topped up.
• Water gauge is an important aid – these tanks have an external water gauge (glass tube or numbered scale), which allows you to directly read the water level. The correct level when the pump turns on should be in the lower quarter of the tank.
• Corrosion from inside – the galvanized coating is not eternal. Aggressive or soft water gradually damages it. After long-term operation, rusty deposits may appear in the water, which is a sign of advanced internal corrosion.
• Cleaning of the air space – for tanks with a maintenance hatch (a lid on top), it is advisable to perform an internal inspection and possible flushing every 2–3 years.
• Scale deposits – hard water deposits limescale on the bottom of the tank. In large tanks (200, 300 liters), this can reach several liters after years. This reduces the effective volume of the tank and can damage the pump if loose particles get into the system.

Stainless steel pressure tanks (with membrane)

A modern and hygienically advantageous option. Examples include Stainless steel pressure tank CH 90 L vertical and its larger variant, Stainless steel pressure tank CH 300 L vertical. These tanks:

• They do not have direct contact between air and water – a membrane separates them, so air does not dissolve and the pressure in the pneumatic part remains more stable over time. Despite this, slow air leakage through the valve or micro-cracks in the rubber can still occur.
• They do not require air topping up as often – but I still recommend checking once a year. A loss of 0.2–0.3 bar per year is quite normal.
• The membrane is a consumable part – this is the most important maintenance task for these tanks. The rubber membrane ages, hardens, and cracks after 5–10 years. Replacement is relatively simple (in tanks with a removable flange), but it depends on the specific tank design.
• The stainless steel shell is durable – it does not require any special attention. Just check the welded joints during the annual inspection (visually) – in the case of aggressive water, point corrosion can cause dark spots to appear.

Small tanks with a membrane (e.g., 24 liters)

Smaller tanks such as the AQUA OLA 24l horizontal pressure tank are installed with smaller pumps and water systems. Their membrane is also a consumable part, but due to the smaller tank volume, the consequences of failure are noticed more quickly – the pump will start switching on very intensively. The advantage is that these tanks can be relatively cheaply replaced entirely in the event of a membrane failure.

Membrane replacement – when and how

Membrane replacement is the most extensive maintenance task you will encounter with pressure tanks. Many owners are not even aware that the membrane is replaceable – they think the entire tank is disposable. In reality, you just need to order the correct membrane (according to the manufacturer and tank volume) and replace it.

How to recognize a damaged membrane:

• Water (not air) comes out of the air valve when pressed
• The pump switches on and off very quickly – practically every 2–5 seconds during water use
• After closing the tap, the pressure drops to zero immediately (no reserve pressure)
• The tank is unusually light – when tapped, it sounds "full" (water is in the pneumatic part)

Membrane replacement procedure (general, depends on tank design):

1. Turn off the pump, close the tap, and completely drain the water and air from the tank
2. Remove the lower flange or top cover – depending on the tank design (most modern tanks have the membrane accessible via the lower flange)
3. Remove the old membrane – it may be firmly stuck to the tank wall or inserted. When dealing with hardened, cracked rubber, use protective gloves
4. Inspect the inside of the tank – if there is corrosion or heavy sediment, clean it before installing the new membrane
5. Insert the new membrane – it must be specifically designed for the tank type (food-grade rubber for drinking water, EPDM or butyl)
6. Tighten the flange evenly in a cross pattern – not all at once in one place, to ensure the gasket seats properly
7. Charge the pneumatic part with air and check the pressure
8. Open the tap, allow the tank to fill, and check the flange for leaks

This task is manageable for a skilled DIY enthusiast, but if you are unsure – it is better to call a service. An improperly sealed flange can cause water leakage under pressure.

Cleaning and disinfection of the pressure tank

This topic is often underestimated in home water systems. A pressure tank for drinking water should meet hygiene requirements. Tanks without a membrane are more important in this regard, as air directly contacts the water. Liquids and biofilm can accumulate on the inner surface.

When to disinfect:

• During the first installation of a new tank (flushing and disinfection before filling)
• After membrane replacement
• If the water starts to smell or have an unnatural color
• After a long break (e.g., a vacation home where the water system was not used for months)
• After floods or well contamination

Disinfection procedure: Drain the tank, prepare a solution of calcium hypochlorite or a special disinfectant for drinking water (e.g., chlorine dioxide solution), pump it into the tank, and let it sit for 30–60 minutes. Then thoroughly rinse with clean water. The entire system must be thoroughly rinsed after disinfection – the water at the taps should smell clean, without chlorine.

Pressure switch inspection and pressure settings

The pressure switch is an electronic or mechanical switch that controls the pump – it turns it on when pressure drops and turns it off when the desired pressure is reached. Although technically part of the pump, not the pressure tank, its function is closely linked. A faulty pressure switch can cause the same problems as a faulty tank.

Signs of pressure switch failure:

• The pump does not switch on even when pressure is low (contacts oxidized or stuck)
• The pump does not start – it switches on and immediately turns off
• The pump runs continuously, even when no water is being drawn (pressure switch fails to shut it off)
• Unstable, fluctuating pressure without an obvious cause, even with properly set air pressure in the tank

Annual pressure switch check includes: visual inspection of contacts (oxidation, corrosion), verification of set pressures (usually adjustable with two springs – larger for minimum pressure, smaller for the min/max difference), and a functional test – manually starting the pump and observing at which manometer values it switches on and off.

Warning signs you shouldn't ignore

From experience, I know that most pump failures and tank-related problems could have been avoided if the owner had noticed these early symptoms:

• The pump switches on every 5–10 seconds during normal consumption – water hammering, damaged membrane or deflated air chamber
• A sudden "thud" in the water supply when opening a tap – hydraulic shock caused by insufficient air cushioning
• Moisture or droplets on the tank's casing – it may be condensation (normal), or a slow leak through a weld or connection
• Rusty or cloudy water – internal corrosion, or sediment from the bottom
• The tank is unexpectedly light even though it should be filled with water – air and water have swapped places, the membrane is defective
• Water pressure in the supply network drops sharply after a power outage and does not quickly recover after the pump is turned on – the tank has lost its reserve capacity
• Gurgling or rumbling sounds in the pipes after the pump is started – air in the system, problem with the discharge side or the tank

A more detailed overview of faults and their solutions can be found in the article Common pressure tank faults and how to eliminate them in this Knowledge Center.

Safety aspects of pressure tank maintenance

The pressure tank operates at a working pressure typically between 2–6 bar. These are values you should not handle without basic safety rules. A few principles you should always follow:

• Never remove connections or flanges under pressure. Always close the valve first, drain the water and air, and only then proceed with mechanical work. A pressure of 4–6 bar can cause serious injury if a connection is released uncontrollably.
• Do not overload the tank beyond its maximum operating pressure – each tank has a manufacturer-specified maximum pressure (typically 6, 8 or 10 bar). Setting the pressure switch above this value is dangerous and illegal.
• The safety valve must be functional and properly set – its trip pressure must be lower than the tank's maximum operating pressure. It must never be blocked or removed "for convenience".
• Use only air or inert gas (nitrogen) – never connect oxygen or other flammable gases to pressurize the tank. Pressure tanks are not designed to work with flammable media.
• Remove an old, rusty or mechanically damaged tank from service – corrosion significantly weakens the tank walls. A crack or explosion in a pressure tank is rare, but a real scenario if maintenance is neglected.

Typical scenarios from practice

Scenario 1 – A summer cottage after winter: A customer opened the cottage in spring, turned on the water system, and the pump ran continuously. Problem: during the winter freeze, the membrane cracked (water inside the membrane froze and tore the rubber). Solution: replaced the membrane, checked the inside of the tank. Lesson: drain the entire tank and pump before winter.

Scenario 2 – A family home, 5-year-old galvanized tank: The water from the tap was brown, the pump switched on every 30 seconds. Problem: internal tank corrosion, air pressure dropped to zero (completely absorbed). Solution: refilling the air provided quick improvement, but the brown water indicated advanced corrosion – it was necessary to replace the tank with a stainless steel one with a membrane. Lesson: galvanized tanks last shorter with aggressive (soft) water, water quality should be checked.

Scenario 3 – New installation, new pump starts immediately: The owner installed the pump himself, bought a small 24-liter tank. The pump switched on too often. Problem: the tank volume was too small for the pump's flow rate. Solution: replaced with a larger tank. Lesson: choosing the correct volume is critical – more on this in the article What pressure tank volume do I need for my home?.

Scenario 4 – A weekend home with a deep well water system: Everything worked fine for years without problems, then a strong water odor appeared. Problem: long inactivity during a heatwave caused bacterial growth in the tank and pipes (stagnant water). Solution: disinfection with chlorinated lime, flushing, checking the air line. Lesson: after long inactivity, always flush and disinfect the entire water system before reuse.

Maintenance records – why keep them

It may seem unnecessary, but in practice, maintenance records are extremely useful. Record the date, measured pressure values, and any work performed. The reasons are practical:

• You will see a trend of pressure drop – if it drops by 0.5 bar in one year and by 1 bar in the next year, the valve is leaking and needs to be replaced
• When selling real estate, you can prove proper maintenance of equipment
• When reporting a malfunction, the record serves as proof of proper care
• A service technician can diagnose the problem faster if they know the tank's history

A simple notebook in the technical room or a photo from your mobile phone with the date is sufficient. Professional equipment has service labels directly on the tank – you can apply the same principle at home.

Most Frequently Asked Questions (FAQ)

How often should the air pressure in a pressure tank with a membrane be checked?

We recommend checking the pressure in tanks with a membrane once a year, ideally in spring after the winter season. The correct value should be 0.2–0.5 bar lower than the switching pressure of the pressure switch (e.g., if the pressure switch activates at 2.5 bar, the air should be at 2.0–2.3 bar). If you have noticed during the year that the pump is switching more frequently, check the pressure sooner – even without a plan. In tanks without a vacuum (galvanized), air pressure must be checked and topped up much more frequently, sometimes every 1–3 months.

Can I replace the membrane myself, or should I call a professional?

Replacing the membrane is technically feasible for a skilled DIY enthusiast, but it depends on the tank's design. For tanks with an accessible bottom flange (most modern types), basic tools and a few hours of work are sufficient. It is important to order an original or compatible membrane made of the correct material (EPDM or butyl for drinking water) and to evenly tighten the flange during installation. If you are new to this, I recommend having the first replacement done by a service technician while you observe the process – you will be able to do the next ones yourself.

What to do if the pressure tank starts leaking?

It depends on where the leak is. If it is dripping from a connection or fitting – tighten or replace the gasket (Teflon tape, pre-formed polyethylene gasket). If it is dripping from a weld seam on the shell – this is not repairable at home, it is a structural failure and the tank must be replaced. If you see moisture on the entire surface of the tank – check whether it is condensation (typical in a cold basement with warm water). Condensation can be eliminated by insulating the tank or improving the room's ventilation.

How long can a pressure tank last without maintenance?

A pressure tank without any maintenance can "function" for 10–15 years, but with significantly reduced efficiency. The membrane degrades, air leaks or is absorbed, corrosion progresses. In practice, most of the problems I encounter come from completely neglected tanks – the owner doesn't even know that something needs to be done. The result: prematurely worn pump, rusty water, burst membrane. Regular annual checks can extend the system's lifespan to 20 years or more.

Is it necessary to service the pressure tank by an officially certified technician?

For standard home water systems and pressure tanks up to 0.5 m³ and a maximum working pressure of 10 bar, Slovak law does not require regular inspections by a certified technician (unlike in industrial pressure tanks). Routine maintenance – pressure checks, air topping up, membrane replacement – can be done by yourself. An exception are tanks larger than 1000 liters or with higher pressure, where different regulations apply. In case of any doubts about the tank's condition, consult a professional.

What to do if water in the pressure tank freezes in winter?

If the technical room is not heated and temperatures drop below zero, water in the tank can freeze. The expansion of ice can crack the membrane, pipes, fittings, or even the tank itself (if it is an older model with thin walls). During thawing, first carefully heat the room (not with an open flame on the tank!), let the water thaw slowly, then check the entire system for possible leaks. Solution for the future: either insulate the pressure tank or drain the entire water system before winter. Instructions for winter storage can also be found in the article Step-by-step installation of a pressure tank for a home water system.

Conclusion: Regular care always pays off

A pressure tank is not a "buy and forget" device. It is a mechanical system that operates in a constant pressure cycle – every day it is inflated and deflated, the membrane bends, and the air changes temperature. This is normal physics and it simply wears out. Unlike a car, where everyone knows that oil needs to be changed, most people do not realize that maintenance exists for a home water system.

The good news is that maintenance costs are minimal – a tire pressure gauge costs just a few euros, and air topping up does not even require a compressor (a bicycle pump with a pressure gauge is sufficient). A membrane for a standard tank costs 20–50 euros and replacement takes one hour. This is negligible compared to the costs of replacing a pump that has worn out due to premature operation, or replacing the entire pressure tank.

Do you have a question about this topic?

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