Frequently Asked Questions

A flow sensor measures the volume of water moving through the main supply line of your irrigation system and sends that data to your smart controller. The controller uses this information to determine whether each zone is operating within its expected parameters. If flow is too high, it may signal a broken pipe or a stuck valve; if flow is unexpectedly low or absent, it may indicate a clogged head or a valve that failed to open.

A flow sensor monitors the pipeline continuously, not only while the system is running. If flow occurs at an unscheduled time, the controller’s logic can advance to the next watering zone or shut the system down entirely and send an alert before water loss becomes significant. Flow sensors conserve water, reduce water costs, and protect landscapes from washouts.

In irrigation, the two terms are often used interchangeably, but there are practical distinctions. A flow meter is a water meter, a device that measures flow volume mechanically and typically displays a running total that must be read manually. Some water meters can be fitted to transmit a signal, but it is only a totalizer, so the reading is not delivered in real time.

A flow sensor, as used in the irrigation industry, refers specifically to a device that detects flow rate and transmits a signal to a controller in real time. This allows the controller to respond automatically, and much faster than it could with a water meter. CST products are irrigation-specific flow sensors, engineered for the underground conditions, water quality, and pressure environments found in real-world irrigation systems.

Yes. A CST flow sensor is designed to work in conjunction with a compatible smart irrigation controller. The sensor provides the flow data; the controller interprets it, takes action, and delivers alerts. If your current controller does not support flow sensing, this is often the right moment to evaluate a controller upgrade alongside sensor installation. Your CST distributor or irrigation professional can help confirm compatibility.

CST manufactures several flow sensor models to address different installation scenarios and pipe materials:

• PVC Flow Sensor — designed for standard PVC main lines; one of the most widely installed sensors in the CST lineup.
• ELF Series (Enhanced Low Flow Sensor) — built for systems with lower flow rates where standard sensors may not read accurately.
• Saddle Flow Sensor — installs on the outside of larger pipe using only a hole saw, ideal for retrofit projects.
• Brass Flow Sensor — designed for applications where brass fittings are required by code or system specification.

The right sensor depends on your pipe material, size, flow rate, and installation conditions.

Yes, and this is one of the most meaningful advantages CST sensors offer over competing products. CST flow sensors are designed to remain in the ground year-round. They do not need to be removed, stored, or reinstalled as part of seasonal winterization and spring start-up. This saves contractors time on every service visit and eliminates the risk of damage during seasonal handling. For property owners, it means lower labor costs and no exposure from a sensor sitting in storage.

Yes. All CST flow sensors can be installed on pipe at any angle. On vertical pipe, a flow sensor can be installed radially, making it easy to service in tight quarters. In most underground installations, the flow sensor is installed upright in a meter pit or valve box, since it will be serviced from above. In mechanical rooms or on pump skids, the sensor can also be angled to make service easier, and in extreme locations such as utility tunnels, it can be installed overhead with the retaining nut facing down.

One word of caution: on vertical or downward-sloping pipe, make sure there is enough back pressure to keep the pipe full. All flow sensors, of any kind, measure velocity and require the pipe to remain full to maintain accuracy.

The flow sensor and master valve should always be installed together, as close as possible to the point of connection (POC) with the water supply. This allows the pair to protect and control the entire piping system. Whether the flow sensor sits before or after the master valve is not critical as long as the two are close together: if the flow sensor detects a problem, the controller will shut the master valve and stop flow either way.

CST recommends a minimum of 10 pipe diameters of straight, unobstructed pipe before the sensor and 5 diameters after it, to prevent turbulence from valves, filters, or fittings from affecting accuracy. Placing the flow sensor before the master valve allows the two devices to be positioned even closer together within that 10-and-5 guideline.

When a pipe breaks, water that should be distributed through sprinkler heads instead discharges freely into the soil at the break point, causing a measurable increase in flow rate above what the active zone would normally produce. The CST sensor detects this elevated flow in real time. The smart controller recognizes the anomaly, closes the master valve to stop water movement through the system, and notifies the property owner or manager by email or text. The entire sequence can happen within minutes of the break occurring.

CST’s management and engineering team has been involved in flow-measurement design and manufacturing for irrigation applications for over forty years. In that time, we’ve investigated many technologies in search of the best combination of performance, reliability, and cost. Every measurement technology has advantages and drawbacks depending on the application it was designed for.

We believe impeller-type sensors offer the performance features that matter most in irrigation: a wide measurement range, very low pressure loss, ease of troubleshooting and repair, self-cleaning operation, and the ability to withstand winterization. Our design experience also delivers reliability in the harsh conditions of underground installation — pressure surges, flow turbulence, and a wide range of electrical demands on the circuitry that powers the sensor and delivers its data. Cost matters too: if a product’s price, or the time required to install or service it, is too high, it won’t get used.

Some manufacturers rely on older, lower-cost technology and sell on price alone, sacrificing performance and reliability. Others have borrowed technologies from different industries, such as ultrasonic measurement. Ultrasonic sensing may work well in other environments, but it is poorly suited to irrigation, where smooth, uninterrupted flow is rare. Entrained air bubbles as pipes refill, and turbulence caused by pumps, pressure regulators, and solenoid valve operation, all disrupt ultrasonic measurement and can produce inaccurate readings.

Marketing claims that these devices are superior because they have no moving parts and can measure down to zero flow are largely beside the point: having no moving parts also means there’s nothing to troubleshoot and no way to check the signal, the wiring, or the controller if a problem arises. CST’s impeller-type sensors, by contrast, can measure down to the practical limits needed by even the smallest drip zones.

We are continuously looking for ways to make our products better. If a superior way to measure flow existed, we would build it. Until then, we’ll keep improving impeller technology.

CST is currently field-testing a wireless flow sensor (WFS) option that will allow a wireless connection between the irrigation controller and the flow sensor / master valve location. The battery-powered sensor will be available in every size and series of existing CST flow sensors. This system will be available soon — watch for announcements.

Yes. CST products are American-made, and the company maintains Build America, Buy America (BABA) compliance, a requirement for many federal, state, and municipal projects. Organizations procuring irrigation equipment for public infrastructure can specify CST sensors with confidence that they meet applicable domestic content standards. For project teams that need documentation, CST can support compliance verification during the specification process.

CST sensors are compatible with a wide range of smart irrigation controllers from major manufacturers; compatibility depends on the signal format your controller requires. The best starting point is to contact CST directly by phone, email, or through the distributor network. CST’s technical team can match you to the correct sensor and confirm what accessories may be needed for your application. Wiring diagrams and technical bulletins are also available on the CST website.

The Pathway S01 is an accessory that allows a CST flow sensor and master valve to be added to an existing irrigation system using the wire infrastructure already in place, without running new dedicated wire. This is especially valuable on retrofit jobs where pavement, hardscape, or established landscaping make trenching for new wire cost-prohibitive or physically impractical. The Pathway device creates a viable path to flow monitoring in situations where conventional wiring would otherwise make a project unworkable.

With the ISO4 Isoflow signal processor, up to four controllers can share a single CST flow sensor and control one master valve. This is a practical solution for larger properties or facilities where multiple controllers manage different zones of the same irrigation system while drawing from a single main supply. Without the Isoflow, each controller would typically require its own dedicated sensor and master valve configuration.

Yes. Individual product FAQs and installation guides are available on our website at creativesensortechnology.com/products — select the product you need help with to find its installation and FAQ guide.

CST technical support is also available by email at info@creativesensortechnology.com and by phone at 508-763-8100 during Eastern business hours. Leave a voice message and calls will be returned as soon as possible.

CST products are available through a network of domestic and international irrigation distributors. CST does not sell direct to end users.

To find a distributor in your area, visit the distributor locator on the CST website or contact CST by phone at 508-763-8100 or by email at info@creativesensortechnology.com.