Analog TDS Water Quality Sensor Kit – 0-1000ppm, Waterproof Probe

The Analog TDS Water Quality Sensor Kit is designed to measure the Total Dissolved Solids (TDS) concentration in water, providing a simple way to monitor changes in water quality using Arduino, ESP32, STM32, Raspberry Pi Pico, and other microcontroller platforms with an analog input.

The sensor provides an analog voltage proportional to the measured TDS level, with a measurement range of 0–1000ppm. It includes a waterproof two-electrode probe and signal-conditioning board, making it suitable for water-quality monitoring, hydroponics, aquariums, filtration systems, and educational projects.

Technical Specifications

• Sensor Type: Analog TDS Water Quality Sensor
• Measurement: Total Dissolved Solids (TDS)
• Input Voltage: 3.3–5.5V DC
• Analog Output: 0–2.3V
• Working Current: 3–6mA
• TDS Measurement Range: 0–1000ppm
• Measurement Accuracy: ±10% F.S. at 25°C
• Signal Type: Analog Voltage
• Excitation Method: AC Excitation
• Signal Board Size: Approx. 42 × 32mm
• Probe Type: 2-Electrode Waterproof Probe
• Probe Cable Length: Approx. 83cm
• Probe Connector: XH2.54-2P
• Controller Interface: 3-Pin Analog Interface
• Mounting Holes: 4 × 3.2mm

What Does TDS Measure?

TDS (Total Dissolved Solids) represents the concentration of dissolved substances in water and is normally expressed in ppm (parts per million) or approximately mg/L for dilute water solutions.

These dissolved substances can include ions from:

Mineral Salts
Calcium & Magnesium
Sodium & Potassium
Chlorides
Nitrates
Other Dissolved Ionic Materials

In general, a higher TDS reading indicates a greater concentration of dissolved ionic substances in the water.

However, a TDS measurement does not identify which specific substances are present.

Analog Output

The signal-conditioning board provides an analog output between approximately 0 and 2.3V.

This signal can be read using a microcontroller ADC and converted into an estimated TDS value through software.

Typical connection:

VCC – 3.3-5.5V DC
GND – Ground
A / AO – Analog Output

For an Arduino UNO, the analog output can be connected to an input such as A0.

For an ESP32, the output can be connected to a suitable ADC-capable GPIO pin.

AC Excitation

The sensor uses an AC excitation signal for the probe rather than continuously applying DC voltage across the electrodes.

This helps reduce electrode polarization and improves stability during water measurements.

Waterproof Probe

The included two-electrode probe is waterproof and designed for immersion in the liquid being measured.

The probe and its cable can be immersed, but the electronic signal-conditioning board and electrical connectors should be kept dry.

The probe should not be used in water above approximately 55°C.

Temperature Compensation

Water conductivity changes significantly with temperature, which means temperature can also affect the calculated TDS value.

This sensor does not include an integrated temperature sensor.

For improved measurements across varying water temperatures, an external waterproof temperature sensor can be added and the measured temperature used for software compensation.

For basic applications without an external temperature sensor, calculations are commonly referenced to 25°C.

Calibration

For better measurement accuracy, the sensor should be calibrated using an appropriate TDS calibration solution with a known concentration.

Calibration is particularly recommended when the sensor is being used for hydroponics, water-treatment experiments, or comparative water-quality monitoring.

Microcontroller Compatibility

The analog interface makes the sensor suitable for development platforms including:

Arduino UNO / Mega / Nano
ESP32
ESP8266 with suitable ADC range
STM32
Raspberry Pi Pico
AVR & PIC Microcontrollers

A standard Raspberry Pi does not have a built-in analog input, so an external ADC is required to read this sensor directly.

Applications

Ideal for water quality monitoring, hydroponics, aquaponics, aquarium monitoring, water filtration systems, reverse-osmosis monitoring, drinking-water experiments, smart agriculture, environmental monitoring, IoT water systems, educational laboratories, Arduino projects, and ESP32 water-monitoring systems.

Important Note

TDS is an indirect measurement based primarily on the electrical conductivity of dissolved ions in water. The sensor does not directly count or chemically identify individual dissolved substances.

A low TDS reading does not automatically mean that water is safe to drink, and a high TDS reading does not identify the type of contamination present. Some harmful contaminants may not significantly affect conductivity or TDS.

This sensor should therefore be used for general monitoring, comparison, education, automation, and DIY projects, not as a certified laboratory or drinking-water safety instrument.

The probe should not be used in water above approximately 55°C, and the electronic signal-conditioning board and connectors must be kept dry.

Package Includes

• 1 × Analog TDS Signal Conditioning Board
• 1 × Waterproof TDS Probe
• 1 × Connection Cable