Waterproof Ultrasonic Distance Sensor for Outdoor and Liquid-Level Projects

The JSN-SR04T 2.0 Waterproof Ultrasonic Ranging Module is the upgrade makers and engineers choose when the standard HC-SR04 isn't enough. Its sealed, waterproof transducer probe can be mounted outdoors, near water, or even partially submerged — making it the right tool for water tank level monitoring, rain detection, outdoor obstacle avoidance, sump pump automation, fish pond control, and any project where moisture or weather would destroy a bare sensor.

Like the HC-SR04, it uses 40 kHz ultrasonic pulses and a simple TRIG/ECHO interface that works with Arduino, ESP32, Raspberry Pi, and virtually any microcontroller. The key difference is the separated, waterproof transducer head connected to the control board via a flexible cable — so only the probe goes into harsh environments while your electronics stay safely protected.

Important: The waterproof transducer probe is sealed and splash/submersion resistant. The main PCB control board is not waterproof and must be kept dry and protected from direct water exposure.

Why you'll love it

Waterproof probe: The sensing head is fully sealed — safe near water, rain, and humidity
Up to 6 meters range: Detects objects from 20 cm to 600 cm with ±1 cm accuracy
3.0V to 5.5V operation: Wide voltage range compatible with both 5V Arduino and 3.3V ESP32 / Pi boards
1 mm resolution: Fine-grained readings for precise level monitoring and distance measurement
75° beam angle: Wider detection cone compared to the HC-SR04's 30° — better for tank walls and irregular surfaces
Same TRIG/ECHO interface as HC-SR04: Drop-in replacement in most code — no library changes needed
Low power consumption: <8 mA working current, ideal for battery-powered outdoor setups

JSN-SR04T 2.0 vs HC-SR04 — which should you choose?

Both sensors use the same ultrasonic principle and TRIG/ECHO interface. Here is how they differ:

Feature	JSN-SR04T 2.0	HC-SR04
Waterproof probe	✅ Yes — sealed transducer	❌ No — bare piezo elements
Operating voltage	3.0V – 5.5V	5V only
Max range	600 cm (6 m)	400 – 500 cm
Minimum range	20 cm	2 cm
Resolution	1 mm	1 cm
Beam angle	75°	<30°
Working current	<8 mA	~15 mA
Best for	Outdoor use, water tanks, rain, liquid level monitoring	Indoor robots, obstacle avoidance, classroom projects
Same code interface	✅ Yes — TRIG / ECHO pins	✅ Yes — TRIG / ECHO pins

What you can build

This sensor is ideal for water tank level monitors, underground cistern sensors, aquarium depth gauges, sump pump float replacements, rain gauge automation, outdoor parking sensors, garden irrigation triggers, flood alert systems, river or canal level loggers, weatherproof robot bumpers, and industrial bin-fill detectors. It is a popular choice for engineering thesis and capstone projects where outdoor or liquid-adjacent sensing is required.

Starter bundles & compatible boards

Pair this sensor with an Arduino Uno, ESP32, or Raspberry Pi from Circuitrocks. Because it operates down to 3.0V, it works directly with 3.3V ESP32 boards without a voltage divider on the ECHO line.

Technical specifications

Model	JSN-SR04T 2.0
Operating Voltage	DC 3.0V – 5.5V
Working Current	<8 mA
Idle Current	~5 mA
Probe Frequency	40 kHz
Maximum Range	600 cm (6 m)
Minimum Range	20 cm
Accuracy	±1 cm
Resolution	1 mm
Measuring Angle	75°
Interface	TRIG (input) + ECHO (output) — digital GPIO, same as HC-SR04
PCB Dimensions	42 × 29 × 12 mm
PCB Color	Blue
Operating Temperature	-20°C to +70°C
Waterproof	Transducer probe only — PCB must be kept dry
Compatible Platforms	Arduino, ESP8266, ESP32, Raspberry Pi, STM32, PIC

Wiring & usage notes

Connect VCC → 3.3V or 5V, GND → GND, TRIG → any digital output pin, and ECHO → any digital input pin. Send a 10 µs HIGH pulse on TRIG, then time the ECHO pulse. Use the same distance formula:

Distance (cm) = Echo pulse duration (µs) ÷ 58

Because the JSN-SR04T 2.0 accepts 3.0V–5.5V, it is safe to connect ECHO directly to an ESP32 GPIO pin without a voltage divider — unlike the standard 5V HC-SR04. Route the cable so only the sealed probe is exposed to moisture; keep the PCB in a dry enclosure.

What's in the box

1 × JSN-SR04T 2.0 Waterproof Ultrasonic Ranging Module (PCB + waterproof probe with cable)

Note: Jumper wires and microcontroller boards are sold separately.

Frequently Asked Questions

What makes the JSN-SR04T different from the HC-SR04? The JSN-SR04T has a waterproof sealed transducer probe that can be exposed to rain, moisture, or splashing water. The HC-SR04 has bare piezo elements that will fail if wet. The JSN-SR04T also has better range (600 cm vs 400–500 cm) and finer resolution (1 mm vs 1 cm).

Can the entire module be submerged in water? Only the transducer probe is waterproof and can be exposed to water. The PCB control board must be kept dry and protected inside an enclosure.

Is this compatible with my existing HC-SR04 code? Yes. It uses the same TRIG/ECHO interface and the same pulse-timing formula. In most cases you can swap the sensor without changing your code.

Does it work with ESP32 at 3.3V? Yes. The JSN-SR04T 2.0 operates down to 3.0V, so it is natively compatible with 3.3V boards like ESP32 and Raspberry Pi — no voltage divider needed on the ECHO pin.

What is the minimum detectable distance? The minimum range is 20 cm. Objects closer than 20 cm may not be detected reliably, which is a design tradeoff of the sealed transducer format.

Can I use this for a water tank level monitor? Yes. This is one of the most common use cases. Mount the probe at the top of the tank pointing downward, keep the PCB outside the tank in a dry box, and read distance to calculate water level.