What is a Gate Valve? Gate, Ball and Butterfly Valves Explained for UK Water Storage Tanks
Every water storage tank system needs a reliable way to control the flow of liquid in and out. Whether you are managing potable water on a construction site, storing effluent on an industrial premises, or running a recirculating aquaculture system, the valves you specify are just as important as the tank itself. Get the valve type wrong and you risk poor flow control, leakage, equipment damage, and costly downtime.
Gate valves are the most widely used isolation valves in UK water supply and storage systems, but they are frequently confused with ball valves and butterfly valves. Each type serves a different purpose, performs differently under different conditions, and suits different tank configurations. This guide explains what a gate valve is, how it works, the parts of a gate valve, the different types of gate valves available, and how gate, ball and butterfly valves compare when used with UK water storage tanks.
What is a Gate Valve?
A gate valve is a type of linear valve used to start or stop the flow of liquid through a pipeline. It is a full-bore isolation valve, meaning that when the valve is fully open, the gate is lifted entirely clear of the flow path, leaving an unobstructed bore the same diameter as the pipe. This produces minimal pressure drop, allows fluid to flow freely with virtually no resistance, and means gate valve has no obstruction to water flow when in the open position.
The gate valve gets its name from the closure element itself: a flat or wedge-shaped gate that slides perpendicularly into the flow stream to block it, acting like a gate closing across a passage. Motion is controlled by a stem connected to a handwheel or actuator. Turning the handwheel raises or lowers the gate within the valve body, opening or closing the flow path.
Gate valves are designed for fully open or fully closed operation only. They are not suitable for throttling or flow regulation. Using a gate valve in a partially open position causes turbulence, erosion of the gate and seats, and premature wear of the body of the valve. Their purpose is simple and specific: to isolate sections of a pipeline or to start and stop flow entirely. Gate valve is commonly used across water supply, effluent storage, industrial pipework, and potable water tank installations throughout the UK.
How Does a Gate Valve Work?
Understanding how a gate valve works starts with the valve construction itself. The main parts of a gate valve are the valve body, the gate, the stem, the bonnet, the seats, and the handwheel or actuator.
The valve body is the outer shell that houses all internal components and connects to the pipeline at each end. It contains the two seats against which the gate seals when the valve closes. Inside the body of the valve sits the gate, either a wedge-shaped or parallel-sided plate that slides vertically across the flow path to control fluid flow.
The stem runs vertically through the bonnet, which is the cap at the top of the valve body that seals the stem from the outside environment and provides access to the valve. The handwheel is fixed to the top of the stem. When the handwheel is turned clockwise, the stem drives the gate downward into the closed position, creating a tight seal against the two parallel seats inside the valve body. When turned anticlockwise, the stem lifts the gate upward until it is fully retracted into the bonnet, leaving the flow path completely clear and the gate valve is fully open.
The stem is typically threaded into the gate or threaded through the bonnet depending on the stem design. This is what converts the rotational movement of the handwheel into the linear movement of the gate inside the valve.
There are two main stem designs. A rising stem moves upward out of the valve body as the valve opens, giving a clear visual indication of valve position at all times, whether the gate valve is open or closed. A non-rising stem design, sometimes called an inside screw, keeps the stem within the valve body throughout operation. Non-rising stem gate valves are preferred for underground or space-restricted installations where vertical clearance above the valve is limited. Gate valves are also available with pneumatic, hydraulic, or electric actuation for installations where manual operation is not practical.
Types of Gate Valves
Understanding the different types of gate valves matters because valve construction and gate design directly affect which applications a gate valve is suited to. The two main types differ in the design of the gate itself.
Wedge Gate Valves
Wedge gate valves are the most common type and the standard gate valve model used across UK water supply systems. The gate is machined at a slight angle to match two inclined seats inside the valve body. This inclined gate design creates a tight, reliable seal as the two halves of the wedge are pressed firmly against the matching inclined seats. Wedge-shaped gate valves are the preferred choice for clean water, potable water, and neutral fluid applications.
Resilient seated gate valves are a widely used variation of the wedge type. They use a rubber-encapsulated wedge that provides an even tighter seal and resilient seated gate valves provide excellent sealing performance across a long service life. Gate valves are resilient seated as standard for isolating potable water and clean neutral fluids across UK water supply and waterworks applications.
A flat gate variant also exists for lower-pressure applications where the full wedge action is not required.
Parallel Slide Gate Valves
Parallel slide gate valves use a flat gate with two parallel seats rather than an angled wedge. The gate is held against the downstream seat by fluid pressure rather than mechanical wedging, which means the valve is used to isolate flow from either direction with equal reliability. Parallel gate valves of this type are also described as having two parallel seats that move lower together as the valve closes, and the gate is used to cut off flow cleanly without the high seating loads of a wedge design.
Knife gate valves are a variation of the parallel slide design, with a sharp-edged gate used for larger valves handling dense fluids, slurries, and dry bulk solids. Metal seated gate valves use a non-ferrous metal face within the valve body and are the correct choice for wastewater, sewage, and effluent applications where rubber seats would degrade. The sluice valve, traditionally used in waterworks and water treatment infrastructure, is also a parallel gate design and remains a widely specified valve for water supply isolation in UK civil water engineering.
Gate Valve vs Ball Valve vs Butterfly Valve: Which is Right for Your Tank?
All three valve types are available as standard fittings for corrugated steel water storage tanks, in inlet and outlet sizes from 2 inches to 12 inches, as part of our accessories range. Whether a gate valve, ball valve, or butterfly valve is the right choice depends on your application, flow requirements, and the liquid being controlled.
Gate Valve
A gate valve is the correct choice when you need a reliable, full-bore isolation valve for water supply with minimal pressure drop and a tight seal when closed. Gate valves are best suited to larger pipelines where fluid needs to be shut off completely and cleanly, and where the valve will not be operated frequently. Gate valves are often specified on mains fill connections, gravity-fed distribution outlets, and primary drainage connections on large storage tanks. Their full-bore design means gate valve has no obstruction to fluid flow in the open position, which makes them the most dependable valve for water supply, effluent storage, and potable water tank applications.
Gate valves are also bi-directional, meaning they can isolate water flow from either direction, a useful characteristic in complex tank installations with multiple inlets and outlets.
Ball Valve
A ball valve uses a rotating ball with a hollow bore drilled through its centre. A quarter turn of the handle rotates the ball so the bore either aligns with the pipeline, with the valve is open and flow unrestricted, or sits perpendicular to it in the closed position. Ball valves provide an excellent seal, give an immediate visual indication of valve position through the handle orientation, and open and close rapidly.
Ball valves are well suited to smaller diameter pipelines and applications requiring frequent operation or fast shut-off. They are a practical choice for tank outlet connections used regularly in day-to-day water management. Ball valves are generally less suitable for larger bore pipelines, where gate valves are the more cost-effective and reliable choice and are used for larger valves throughout the waterworks and storage industry.
Butterfly Valve
A butterfly valve uses a disc mounted on a rotating shaft running through the centre of the pipe. A quarter turn of the actuator rotates the disc from parallel to the water flow, fully open, to perpendicular to it in the closed position. Butterfly valves are compact, lightweight, and cost-effective, making them particularly practical in larger diameter applications where space and weight are considerations.
Unlike gate valves, butterfly valves can modulate or throttle fluid flow as well as providing on/off isolation. However, the disc remains within the flow path even when the valve is fully open, creating a small but permanent pressure drop and a restriction that gate valves do not have. For slurry or highly viscous liquids, this obstruction can cause material build-up. Butterfly valves are also more susceptible to water hammer than gate valves because of their faster closing speed.
Gate Valves in UK Water Storage Tank Applications
Gate valves for water supply have been a standard fitting on UK water storage and distribution systems for over a century. They are used to isolate specific sections of a water supply network during maintenance, control water flow between interconnected tanks, protect pump equipment by providing clean shut-off upstream and downstream, and allow access to the valve and tank system for inspection and maintenance.
On a Butek Tanks corrugated steel water storage tank, gate valves are most commonly specified on larger outlet connections where full-bore fluid flow with minimal restriction is the priority: mains fill connections, gravity-fed distribution outlets on potable water tanks, and primary drainage outlets on effluent and slurry storage systems. Our accessories range includes gate, ball and butterfly valves in all inlet and outlet sizes, available in a variety of materials including galvanised steel and PVC to suit the liquid being stored.
For tanks storing potable water, resilient seated gate valves are the correct specification. For effluent and trade wastewater tanks, metal seated gate valves resist degradation from the chemical content of the stored liquid. For slurry and digestate storage, knife gate valves handle the dense, viscous nature of the material without obstruction to flow.
Valve selection links directly to liner choice. A corrugated steel tank fitted with a Butyl rubber liner for potable water storage requires valves and fittings compatible with drinking water contact. Tanks fitted with a Landflex ES liner for industrial effluent storage require chemically resistant valve materials. Our team specifies valves and fittings as part of the overall tank design, ensuring every component is matched to the liquid and the application.
UK Regulations and Standards for Valves in Water Systems
Valves used in potable water systems in the UK must comply with WRAS (Water Regulations Advisory Scheme) requirements under the Water Supply (Water Fittings) Regulations 1999. Any valve or fitting connected to the mains supply must be WRAS-approved to ensure the materials do not contaminate stored water. This applies to gate valves, ball valves, butterfly valves, and all associated fittings on a potable water tank.
For trade effluent and industrial applications, valve specifications must be compatible with the Environment Agency discharge permit conditions and the nature of the stored liquid. Valves on agricultural slurry and digestate tanks must meet the structural and containment requirements of the Silage, Slurry and Agricultural Fuel Oil (SSAFO) regulations.
Frequently Asked Questions About Gate Valves
What is a gate valve used for?
A gate valve is used to isolate sections of a pipeline or to start and stop flow completely. It is a full-bore isolation valve suited to water supply networks, effluent storage tanks, potable water systems, and industrial pipework where minimal pressure drop and reliable sealing in the closed position are the priority. Gate valve is commonly used wherever dependable full-bore isolation is needed.
What is the difference between a gate valve and a ball valve?
Both are full-bore on/off isolation valves but they operate differently. A gate valve uses a linear sliding gate inside the valve body and requires multiple turns of a handwheel to open or close. A ball valve uses a rotating ball and opens or closes with a single quarter turn. Ball valves are faster to operate and better suited to frequent use on smaller bore connections. Gate valves are more reliable for larger bore isolation where operating frequency is low and full-bore fluid flow is critical.
Can a gate valve be used for flow control?
No. Gate valves are designed for fully open or fully closed operation only. Using a gate valve in a partially open position causes erosion of the gate and seats inside the valve, vibration, and premature failure of the valve body. For flow regulation or throttling, a butterfly valve or dedicated control valve should be specified instead.
What is a rising stem gate valve?
A rising stem gate valve has a stem that moves upward out of the valve body as the valve opens, giving a clear visual indication of valve position at all times. A non-rising stem gate valve keeps the stem within the valve body and is the more common choice where vertical space above the valve is restricted, such as in underground installations.
What is a resilient seated gate valve?
A resilient seated gate valve uses a rubber-encapsulated wedge that provides a tight seal against the seats inside the valve. It is the standard type for isolating potable water and clean neutral fluids in UK water supply systems. Resilient seated gate valves provide excellent sealing performance and a long service life in clean water applications and gate valves are resilient seated as standard across the UK waterworks industry.
Which valve is best for a water storage tank?
The right valve depends on the application. Gate valves are best for large-bore isolation where full-bore fluid flow and minimal pressure drop matter. Ball valves suit smaller, frequently operated connections. Butterfly valves are well suited to large-diameter outlets where space is limited and throttling is useful. Our accessories range includes all three types, specified to match the tank, liner, and application.
Conclusion
A gate valve is a full-bore isolation valve designed to start and stop water flow reliably with minimal pressure drop, making it one of the most important components in any water storage tank system. Understanding the different types of gate valves and how gate, ball and butterfly valves compare ensures every connection on your tank is correctly specified for its purpose, whether you are storing potable water, trade effluent, slurry, or any other liquid. At Butek Tanks, we have been designing and manufacturing corrugated steel storage tanks since 1965. Our accessories range includes gate, ball and butterfly valves in all sizes and materials, specified as part of a complete tank solution alongside our liner kits and roof kits. Contact our team today to arrange a free site survey, or explore our full range of tank accessories and fittings.