Sous Vide Cooker: Precision Temperature Water Bath

Sous vide cooking immerses food in precisely temperature-controlled water for perfectly cooked results every time. A DIY sous vide cooker with PID control costs under ₹2,000 and matches the performance of commercial units costing ₹5,000-15,000. This guide covers building a precision temperature water bath for sous vide cooking.

What Is Sous Vide Cooking?

Sous vide (French for “under vacuum”) involves sealing food in a bag and cooking it in a water bath at a precise temperature — typically 50-85°C. The water temperature equals the final food temperature, so you cannot overcook. A steak cooked at 57°C for 1-4 hours is medium-rare edge to edge, with no guesswork.

Precision Temperature Requirements

Sous vide demands ±0.5°C accuracy:

• Rare steak: 52-54°C
• Medium-rare steak: 55-57°C
• Medium steak: 58-62°C
• Chicken breast: 63-65°C (pasteurised after 1+ hour)
• Eggs: 63°C for 45 min (perfectly soft), 75°C for 13 min (soft boiled)
• Vegetables: 83-85°C

A 1°C difference between rare and medium-rare steak demonstrates why PID control is essential — ±5°C thermostat cycling is not acceptable.

Components for the Build

• DS18B20 waterproof sensor (₹58) — submerged in the water bath
• Arduino Uno (₹193)
• SSR 25A for heater control
• Heating element: 1kW immersion heater rod (₹200-400) — standard Indian “instant water heater”
• Small submersible pump (₹100) for water circulation
• Container: any large pot or insulated cooler box (10-20 litres)

PID Temperature Controller

The DS18B20 provides 0.0625°C resolution — more than sufficient for sous vide. The Arduino PID library controls the SSR that switches the immersion heater. With proper tuning, the water temperature stays within ±0.2°C of the set point.

PID tuning for water baths: Kp=500, Ki=0.5, Kd=100 is a good starting point. Water has high thermal mass (slow response), so the integral term needs time to accumulate. Window size: 5 seconds for the SSR time-proportional control.

Water Circulation Design

Water circulation is essential for uniform temperature. Without circulation, the water near the heater can be 5-10°C hotter than the water near the food. A small submersible pump (₹100) continuously circulates water, ensuring even temperature throughout the bath.

Building the Immersion Unit

Mount the heater rod and temperature sensor through a 3D-printed or fabricated lid that clips onto the container rim. The pump sits at the bottom. The Arduino and SSR mount in a dry enclosure above the water line.

For a simpler build, use an insulated container (cooler box) — better insulation means the heater runs less, improving temperature stability and saving power.

Recommended Components

Cooking Guide and Tips

• Food safety: Cook at 54.4°C+ for at least 1 hour to pasteurise most pathogens. Below 54.4°C, limit cooking time to 2.5 hours.
• Vacuum sealing: Use zip-lock bags with the water displacement method (lower bag into water with zip open, water pushes air out, then seal). No vacuum sealer needed.
• Searing: Sous vide gives perfect internal temperature but no browning. Finish steaks and chicken with a 60-second sear in a blazing hot cast iron pan.
• Indian recipes: Sous vide chicken tikka at 63°C for 2 hours gives incredibly juicy results before finishing in the tandoor or oven.