Do you know the difference between a bladder tank and a pressure tank? If not, you’re not alone.
A bladder tank is a water storage tank that uses a rubber membrane or diaphragm to separate the inside of the tank from the water outside.
On the other hand, a pressure tank is a water storage tank that uses compressed air to create pressure and push water into your home’s pipes.
The main differences between bladder tanks and pressure tanks are tank size, maintenance, and overall quality.
What is a bladder tank?
A bladder water tank is a storage tank used to collect and store rainwater. This stored water can be used during dry spells when the main water supply is unavailable.
Water collected by a bladder tank has many benefits since it doesn’t pick up any contaminants from outside, which can contaminate it later. In addition, storage tanks can retain their shape, even when full of water.
They can expand as needed to accommodate more water during periods when it has been raining heavily.
The collected water can be used to meet the home or property’s needs when the main supply is unavailable.
The significant advantage of these tanks is that they will not pick up any additional contaminants from outside sources, which could affect the water quality.
Bladder tanks come in many shapes and sizes depending on your individual needs. One type of bladder tank is made from a flexible material that can expand and contract as necessary to accommodate the water volume.
However, another type of bladder tank is made from a thicker, more rigid material and will maintain its shape regardless of the amount of water stored in it.
Moreover, a bladder tank is a storage tank that uses compressed air to separate the liquid contents from their container.
The design of these tanks involves an outer shell, within which sits the bladder, or membrane, made out of a suitable material such as rubber or some plastic polymer.
When empty and collapsed, the bladder is contained within its outer casing. However, once the liquid has been introduced into the tank, it causes pressure on the bladder material.
The bladder tank is also known as a water saver tank. It is a storage unit that holds the excess or surplus of water when there is a need for it in the home’s plumbing system.
This type of tank can also help prevent flooding by directing back to your water supply line, overflowing from the toilet bowl or other faucets in your house.
The bladder tank is an integral part of the plumbing system because it stores extra water, allowing you to save and conserve this resource for future use.
Because of its construction, it is most commonly used as a toilet-flushing device inside houses and buildings where installing a conventional pumping system would be too expensive or impractical.
What is a pressure tank?
A pressure tank is a container used to hold a fluid under pressure. It plays a vital role in running water supplies, air conditioning, and refrigeration systems.
A tank is usually connected to two major components: one that produces pressure, such as an electric pump or compressor, and another that uses the pressure it produces.
Examples include home hot-water tanks, air compressors for paint sprayers and compressed-air tools, roof dehumidifiers, HVAC equipment including furnaces and boilers, fire sprinkler system pumps, and swimming pool filters.
Pressure tanks are commonly made from steel or polyethylene plastic. The tank must have some form of rigid wall that can support the weight of whatever liquid it contains and resist all possible pressure.
The tank also has a cover and an opening; this may be referred to as a “manhole.” Failure to close the maintenance hole during operation can result in serious injury, death, or property damage.
The tank’s size and shape are primarily determined by what it is used for and how much liquid it holds.
Tanks that store relatively small amounts of water will often have circular or round shapes, while tanks with more significant amounts of water will have more boxlike forms with flat sides.
Even larger tanks may be cylindrical, such as fire sprinkler systems, which may contain many thousands of gallons.
Tank shape is also determined by the liquid being stored; for example, vertical tanks are often used to store water to reduce its overall surface area (to minimize evaporative losses), whereas horizontal tanks are often used to hold oil or other hydrocarbon products.
Modern pressure tanks use a rubber, neoprene, or polyurethane diaphragm. A diaphragm tank can be considered an air-filled chamber surrounded by a rubber membrane with only one opening at the top for filling purposes that can not be removed during operation.
This arrangement keeps air from the tank outside and fluid from inside the tank (the “chamber”) from escaping and prevents water from getting into primary lines that may be damaged. Some diaphragm tanks use an expansion bulb to increase their capacity.
A pressure tank has some inherent disadvantages: if the fluid is a liquid under heat, it will expand as the temperature rises and contract when cooled.
Depending on its size, it may be impossible to fill or drain completely; conversely, excessive temperature variation can cause damage from freezing or overheating.
To function correctly, tanks need pressure and volume sensors to maintain balance (resting state) concerning each other and prevent overpressure failure at either component boundary.
A typical application for tanks is providing water pressure to homes: water enters a gravity-feed system through a valve on a city water line and flows into the bottom of the pressure tank, where it displaces air as it rises to fill up most of the space inside the tank.
The air above this rising water creates positive pressure that lines can be run off from, so when no water is being used, there is plenty of “headroom” inside the pipes (pressure) to allow water to flow out if needed.
This air and water inside the tank also provide a cushion that prevents excessive shock when the valve is opened between two lines for any reason.
If there were no air in the system, opening this valve would cause a surge of high pressure that could damage nearby pipes; with an air cushion present, it creates a small amount of back pressure (a constant negative pressure) as long as the pump is running which helps protect these lines from too much pressure.
The contents of tanks are generally not under very high pressure other than their weight. They are filled with gas rather than liquid when they are pressurized above atmospheric pressure.
This has many significant advantages: pure water cannot even be frozen by most users until its pressure is raised above its standard boiling point, and water (or other liquids) can be heated to a high temperature without vaporizing.
This makes piping simpler and less expensive since it does not require insulation or special construction methods. It also allows liquid under pressure to use otherwise unusable heat sources such as solar energy.
However, keeping gas under pressure requires complex techniques that are impractical in many applications, even when the gas has been cooled below room temperature to make it more condensable.
What are the differences between a bladder tank and a pressure tank?
When deciding between a bladder tank and a pressure tank, it is essential to consider many factors. You don’t have to do any research as we’ve compared the two in all the essential aspects.
1. Tank size
The first significant difference between a bladder tank and a pressure tank is the size. Pressure tanks are far bigger than in the case of bladder tanks.
The main reason is that pressure tanks work like a reserve – they only kick in when the system is under stress, i.e., when water demand exceeds supply and pressure drops below what it should be.
A bladder tank cannot serve this purpose since its size is smaller. In addition, you can use a large pressure tank to store extra hot water during peak hours (when there is less demand) and then redistribute this hot water during low-demand hours or overnight.
2. Maintenance
One of the major differences between a pressure tank and a bladder tank is that a pressure tank requires much more maintenance than a bladder tank.
A pressure tank is typically made from galvanized steel, which can easily rust or become waterlogged over time.
Because of this, it needs to be inspected regularly by a professional to make sure no damage has occurred. In contrast, a bladder tank uses an inner rubber membrane instead of metal, making it much less likely to rust or corrode over time.
Furthermore, since a bladder tank doesn’t use metal components, it is also easier and less expensive to repair if anything goes wrong with it.
3. Water delivery control
One of the main advantages of using a pressure tank over a bladder tank is that it offers greater water delivery and usage control.
In contrast, a bladder tank lacks this level of control because it relies on water pressure flow and volume to generate usable water from the faucet.
For example, if you have a high demand for water at one time—for instance, if someone turns on multiple taps or uses an appliance like the dishwasher—an empty bladder will not be able to keep up with all of that supply due to its limited capacity.
On the other hand, a well-functioning pressure tank would have no problem meeting the demands of multiple users at once.
4. Overall cost
Remember that a traditional, simple pressure tank system is often more affordable than a bladder tank, which isn’t the case with a diaphragm pressure tank.
A traditional pressure tank system consists of a steel tank filled with water, allowing it to maintain constant pressure within the home’s water lines.
This pressure tank typically costs less than $100 and can last many years with proper maintenance.
However, one downside to this type of pressure tank is that if the home experiences even a small amount of leakage, it can allow air into the system and disrupt the system’s ability to maintain consistent water pressure.
In contrast, a bladder tank uses an inner bladder made from rubber or plastic that transfers water from an outer chamber when needed.
This type of tank typically costs more than $200 and must be replaced about every ten years due to wear and tear.
Bladder tank vs pressure tank: Are they the same?
The answer to this question would be no. While these water tanks have similar roles, they do not offer the same efficiency level.
While a traditional pressure tank is more affordable than the bladder tank, it isn’t as durable as a diaphragm pressure tank which can be pretty pricey.
Quality pressure water tanks also offer a higher level of water control. On the other hand, they require more upkeep, as the galvanized steel can often rust or become waterlogged.
It is also important to mention that pressure tanks are often larger than bladder tanks, allowing them to act as a reserve.
David Kessler is a CSLB licensed contractor with over 25 years of experience. He is specialized in home building, construction, and electrical works; he also has a keen eye for interior design and, over the years, has collaborated with various architects.
