Knowing how much water is left in a rainwater tank matters for everything from garden watering restrictions to knowing when a pump is about to run dry. Rain Harvesting's tank gauge range covers four genuinely different ways to read a tank's level, and the right one depends less on budget and more on where you'll actually be standing when you need to check it.
Tank-top dial: Tank Gauge and Tank Gauge XL
The basic Tank Gauge (TATG02, $25.89) sits on top of the tank and gives a simple mechanical reading — no power, no batteries, nothing to pair. It's the cheapest option and it works, but you have to be at or near the tank to read it. The Tank Gauge XL (TGXL01, $49.91) is the same idea with a larger dial and extended reach, making it readable from further away on a bigger tank — a reasonable upgrade if the standard dial is proving too small to read without walking right up to it.
Side-wall mounted: Express vs Guided
Both side-wall gauges move the reading point down to eye level on the side of the tank, with a float-and-counterweight mechanism and a red reflective band that's visible from a distance at any time of day. The Side Wall Express (TGSW01, $139.90) is the standard version. The Side Wall Guided (TGSW02, $154.90) houses the counterweight inside the mounting pole so only the float itself sits in the tank — Rain Harvesting markets this specifically as more stable in windy conditions, where an exposed counterweight on the standard version can swing and give a jumpy reading. If the tank sits in an open, exposed spot, the extra $15 for the guided version buys a steadier read; in a sheltered position the Express is the simpler choice.
Longreach: for taller tanks
The Longreach Tank Gauge (TATG10, $167.99) uses extendable stainless steel pole sections and an adjustable mounting base, with extra pole sections (TATG11/TATG12, $34.90 each) sold separately for tanks too tall for the standard reach. This is the one to reach for once a tank's height outgrows what the Express or Guided gauges are built for, rather than trying to make a shorter gauge work with a stretch.
Going smart: Bluetooth and Sigfox
The Smart Tank Gauge Float (MGTG1BL, $299.89) and Tank Gauge Plus Remote (MGTG1RC4, $299.89) both report tank level to the Rain Harvesting phone app instead of relying on a visual read, for tanks up to 4m in height. The Bluetooth-only Smart float needs you within Bluetooth range to pull a reading; the Plus Remote adds Sigfox connectivity for off-site monitoring (12 months included, then around $25/year) and updates every 10 minutes with custom level alerts. If you only ever check the tank from the house or yard, the plain Bluetooth float plus the Wi-Fi Adaptor (WIFI01, $19.90) — which relays Bluetooth readings onto your home Wi-Fi — gets you app-based monitoring without a Sigfox subscription at all. Sigfox only earns its keep if you need to check the tank from somewhere the home Wi-Fi and Bluetooth range can't reach.
Frequently Asked Questions
What's the difference between the Tank Gauge and Tank Gauge XL?
Same mechanical, no-power design — the XL just has a larger dial and extended reach, making it easier to read from a distance or on a larger tank.
Do I need a side-wall gauge, or will the tank-top dial do?
The tank-top dial is fine if you're happy walking up to the tank to check it. A side-wall gauge moves the reading to eye level and is visible from a distance via its reflective band, which suits tanks you want to check at a glance without climbing up or walking right over.
How does the Smart Tank Gauge Bluetooth float differ from the Tank Gauge Plus Remote?
Both report to the Rain Harvesting app, but the Bluetooth-only float needs you within Bluetooth range of the tank. The Plus Remote adds Sigfox connectivity so it can report when you're off-site, for a small annual subscription after the first 12 months.
Can I add Wi-Fi to the Bluetooth smart gauge later?
Yes — the Wi-Fi Adaptor pairs with the Smart Tank Gauge Float over Bluetooth and relays its readings onto your home Wi-Fi network, so you get app-based remote monitoring without needing the Sigfox-equipped Plus Remote model.