Build an Automated Water‑Drinking Reminder Bot with OpenClaw in Minutes

Background

The author needed a free alternative to a paid water‑reminder app and decided to build a custom solution using an OpenClaw server, which provides a programmable 24‑hour‑online WeChat bot.

Prerequisites

OpenClaw installed on a server

WeChat channel (openclaw‑weixin) configured

At least 4 GB free disk space

Quick Start

The repository for the tool is https://github.com/Jackson0714/openclaw-water-reminder. The core script is water_reminder.py.

Step 1 – Upload the Script

Copy water_reminder.py to the OpenClaw workspace:

# Connect to your server and create the scripts directory
mkdir -p ~/.openclaw/workspace/scripts
# Upload the script to that directory (e.g., using scp)

Step 2 – Initialise the Data File

Run the script once to create water_tracker.json:

python3 ~/.openclaw/workspace/scripts/water_reminder.py reset

Expected output: 已重置 ("Reset").

Step 3 – Create the Hourly Cron Job

Find your WeChat account ID with: openclaw channels list Then add a cron task (replace YOUR_ACCOUNT_ID with the actual ID):

openclaw cron add \
  --name "water-reminder" \
  --description "Every hour reminder from 8:30 to 16:30" \
  --cron "30 8-16 * * *" \
  --tz "Asia/Shanghai" \
  --session isolated \
  --tools exec,read \
  --message 'You are a water‑reminder assistant. Read /root/.openclaw/workspace/water_tracker.json to check today\'s progress.

If the goal (>=2000ml) is reached or a reminder has already been sent today, reply "SKIP".
Otherwise, send a WeChat message with the current amount and the remaining volume. After sending, execute:
python3 -c "import json, sys; d=json.load(open(\'/root/.openclaw/workspace/water_tracker.json\')); d[\'reminded_today\']=True; json.dump(d, open(\'/root/.openclaw/workspace/water_tracker.json\',\'w\'), ensure_ascii=False, indent=2)"' \
  2>&1

Step 4 – Verify the Setup

# Manually trigger the reminder
openclaw cron run $(openclaw cron list --json | grep -o '"id":"[^"]*"' | head -1 | cut -d '"' -f4)

# Check current water intake
python3 ~/.openclaw/workspace/scripts/water_reminder.py status

# Generate a full daily report
python3 ~/.openclaw/workspace/scripts/water_reminder.py report

Usage

Interact with the bot in WeChat (or any configured channel) by sending the following messages: 喝了300ml → Bot replies "✅ Recorded! Today: 300ml, 1700ml left" 喝了500ml → Bot replies "✅ Recorded! Today: 800ml, 1200ml left" 今天喝了多少 → Bot replies "📊 Today: 800ml / 2000ml, 1200ml remaining" 喝水报表 → Bot replies with a detailed daily report including a progress bar.

Customization

Change Daily Goal

Edit water_tracker.json and modify the goal_ml field, e.g.:

{
  "goal_ml": 2500
}

Adjust Reminder Time Window

Edit the cron job:

# Example: 9:00‑20:00 every 30 minutes
openclaw cron edit YOUR_JOB_ID --cron "0,30 9-20 * * *"

Change Reminder Frequency

# Hourly (default)
--cron "30 8-16 * * *"
# Every 30 minutes
--cron "0,30 8-16 * * *"
# Every 2 hours
--cron "30 8-16/2 * * *"

Delete the Reminder Task

# List task IDs
openclaw cron list
# Remove a task
openclaw cron rm YOUR_JOB_ID

File Overview

water_reminder.py

– Core tracking script ~/.openclaw/workspace/water_tracker.json – Auto‑created data store

Data File Format

{
  "date": "2026-04-18",
  "total_ml": 142,
  "goal_ml": 2000,
  "reminded_today": false,
  "log": [
    {"time": "07:46:42", "ml": 82},
    {"time": "07:55:20", "ml": 60}
  ]
}

Command‑Line Reference

# Check status
python3 water_reminder.py status
# Add water amount (debug)
python3 water_reminder.py add 300
# Generate report
python3 water_reminder.py report
# Reset today’s data
python3 water_reminder.py reset
# List cron jobs
openclaw cron list
# Manually trigger a reminder
openclaw cron run YOUR_JOB_ID
# View cron run history
openclaw cron runs --id YOUR_JOB_ID

FAQ

Q: No reminder received? Verify the cron job is enabled with openclaw cron list and ensure enabled: true.

Q: Should reminders run on weekends? The default schedule includes weekends. To limit to weekdays, change the cron expression to --cron "30 8-16 * * 1-5".

Q: Can I change the daily water goal? Yes, edit the goal_ml field in water_tracker.json.

Project Structure

water-reminder/
├── README.md   # This document
└── water_reminder.py   # Core script