Understanding Your Caravan’s Water Monitoring Systems

When you’re free camping, knowing how much water you have left is just as important as knowing your battery level. Run out of water and your trip to that beautiful bush camp is over. A water monitoring system tells you how full (or empty) your tanks are, so you can make informed decisions about when to leave, when to conserve, and when to top up.

Types Of Water Monitoring

Sender-based gauges: The most common factory-fitted system. A sender unit inside the tank measures the water level and displays it on a gauge panel inside the van. These are typically simple (showing quarter, half, three-quarter, full) rather than precise. They’re adequate for general awareness but can be inaccurate if the van isn’t level or if the sender is affected by tank shape.

External ultrasonic sensors: Mount on the outside of the tank and use ultrasonic pulses to measure water level without any in-tank components. More accurate than sender-based systems and no risk of contaminating the tank.

What We Recommend

Mopeka Pro Water Tank Sensor (Best Standalone, $80 to $120 per sensor): Ultrasonic sensor that sticks to the bottom of polyethylene tanks. Connects via Bluetooth to your phone or integrates with Victron GX systems and Simarine displays. Accurate, affordable, and no drilling required. If you already have a Mopeka gas sensor, these use the same app.

GoFurther Water Level Indicator (Good Mid-Range, $100 to $150): Australian-designed external ultrasonic sensor with a dedicated display panel. No in-tank components, no contamination risk. Shows level as a percentage. Well-suited for caravans where you want a permanent mounted display rather than checking your phone.

Simarine Pico (Premium All-In-One, $400 to $500): Monitors water tanks, battery, solar, and temperature from a single touchscreen display. Supports multiple tank sensors. The premium option for travellers who want everything on one screen. Expensive, but replaces multiple individual monitors.

BM Pro BatteryPlus35 (Premium All-In-One, $350 to $450): Australian-made combined battery and water tank monitor with a panel display. Shows battery state of charge and water tank levels simultaneously. Good Australian support and well-proven in the caravan market.

All-in-one monitoring systems: If you’re upgrading your battery monitor anyway, premium systems like the Simarine Pico and Redarc RedVision ($400 to $800) can handle water tank monitoring too, giving you comprehensive oversight of all systems from one screen or app.

The manual method: Knock on the side of the tank. A full section sounds solid; an empty section sounds hollow. It’s surprisingly effective and costs nothing, but requires you to crawl under the van.

Is Monitoring Worth Upgrading?

If your factory gauge works and gives you a reasonable indication, it’s probably adequate for caravan park travel with regular refills. If you free camp regularly and need to manage water carefully over 3 to 5 days, a more accurate system is worth the $80 to $200 investment. Knowing you have 40% left versus “somewhere around half” makes a meaningful difference in planning.