pH ORP DS18B20 Circuit


Yes — a few sensors fit this board architecture well because you already have 3.3V, GND, I2C, 1-Wire, ADS1115 differential analog inputs, and high-impedance probe conditioning.
Good matching additions:

Table


SensorBest InterfaceWhy it matches
EC / TDS / conductivity probeExtra analog front-end + ADS1115 or separate ICCommon companion to pH/ORP for water quality. Needs AC excitation, so it is more complex than pH/ORP.
Dissolved Oxygen (DO) probeAnalog front-end + ADCUseful for water quality. Probe type matters: galvanic/polarographic/optical. Analog DO needs careful conditioning.
Turbidity sensorAnalog or digital moduleEasier add-on; can feed ESP32 ADC or ADS1115 if a channel is free.
Water temperature sensor, second DS18B20Same 1-Wire DQ busVery easy. Multiple DS18B20 sensors can share the same DQ line.
Water level / float switchDigital GPIOSimple safety/status input. Needs an extra J2 pin or separate connector.
Leak detector / wet contact sensorDigital/analog GPIOUseful for enclosure or tank monitoring.
Pressure sensorI2C or analogUseful if measuring pipe/tank pressure. Prefer I2C 3.3V sensors.
Flow sensorDigital pulse GPIOUseful for dosing/flow monitoring. Needs one ESP32 GPIO input.
Best recommendation for your current project:
  1. EC/TDS sensor — most useful companion to pH + ORP, but requires new analog circuitry.
  2. Second DS18B20 — easiest; no schematic change needed except maybe documenting multiple sensors on the same DQ bus.
  3. Turbidity sensor header — practical and beginner-friendly if you use a module.
  4. Flow sensor or float switch header — useful, but J2 would need extra GPIO pins or a second connector.
I would not add all of them to this same board unless you expand the connector/header plan. For your current clean 5-pin ESP32 interface, the easiest “no major redesign” upgrade is multiple DS18B20 sensors on the same DQ line.
Compare sensor options
Add EC/TDS planning
Add turbidity header
Multiple DS18B20 guide
Update docs options

U1
C4
Capacitance
1 µF
R12
Resistance
1000000 Ω
R3
Resistance
1000000 Ω
R11
Resistance
4700 Ω
C1
Capacitance
100 nF
C8
Capacitance
100 nF
R6
Resistance
1000 Ω
C17
Capacitance
10µF
R5
Resistance
1000 Ω
R10
Resistance
1000 Ω
C2
Capacitance
100 nF
C18
Capacitance
100nF
C10
Capacitance
100 nF
R9
Resistance
1000 Ω
C6
Capacitance
100 nF
R8
Resistance
10000 Ω
C11
Capacitance
100 nF
R14
Resistance
10000 Ω
C7
Capacitance
100 pF
C13
Capacitance
100 pF
R4
Resistance
1000 Ω
R13
Resistance
1000 Ω
R2
Resistance
100000 Ω
C16
Capacitance
100 nF
C14
Capacitance
100 nF
C12
Capacitance
100 nF
C9
Capacitance
100 nF
R1
Resistance
100000 Ω
C3
Capacitance
10 µF
C5
Capacitance
10 µF
R15
Resistance
10Ω
C15
Capacitance
100 nF
R7
Resistance
10000 Ω
J1
J3
J2
U2
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J5
ESP32-C3 ADS1115 pH ORP Sensor Interface 4412 thumbnail