Had a job last year on Hodgson Street in Ocean Grove, a private collector’s converted garage storage room, timber crates stacked on pallet racking, humidity controller running, the lot. Client had two water sensors mounted on the wall at about knee height, batteries fresh, all lights green. Problem was the leak that got him three months earlier came up through a cracked slab joint under the second rack from the door. Both sensors sat a metre and a half from where the water actually pooled. He’d bought good gear and put it in the wrong spot, which in this trade is worse than buying cheap gear and getting the spot right.
Water sensors are cheap compared to the collection sitting above them. Placement is where the job is actually won or lost, and it’s the bit almost nobody thinks through properly.
Water doesn’t rise the way people assume #
Most people picture a flood the way it looks on the news, water climbing evenly across a floor. In a storage room it rarely works like that. Water finds the lowest point in the room and pools there first, and slabs are never perfectly flat. Concrete floors have falls built into them for drainage, sometimes deliberate, sometimes just settling over 30 or 40 years. i’ve walked into rooms where the low point is nowhere near the door, nowhere near a drain, just some odd dip in the middle of a rack run because the original builder didn’t level the pour properly.
Before I put a single sensor down I get a torch and a spirit level and actually check where water would go if it were poured on that floor right now. Not where it looks like it should go. Where it actually would.
Floor level sensors, but not just anywhere on the floor #
The mistake with the Ocean Grove job, and I’ve seen it a dozen times since, is treating floor-level placement as a single decision rather than several. A storage room with racking needs sensors at every genuine low point, not one sensor near the door because that’s convenient for the technician doing the install. That’s an install done for the paperwork, not for the room.
Under racking is the spot people skip because it’s awkward to get to and awkward to service. It’s also usually the first place slow leaks show up, because nobody’s walking through there daily to notice a damp patch the way they would near a doorway.
Behind stored items, not just in front of them #
This is the one that catches out otherwise decent installs. A sensor mounted on open floor two metres from a rack looks tidy on a site plan. It does nothing if the leak originates behind the rack, against the back wall, where rising damp or a failed downpipe seal has been working away for months before anyone notices a smell.
I did a consignment storage fit-out for a gallery a few years back where stock volume changes week to week, boxes in, boxes out, whole layout shifting. That kind of environment makes fixed sensor placement genuinely hard, because the low-risk spot on Monday can be stacked floor to ceiling by Friday. We’ve written more on that specific problem in our piece on security considerations when consignment stock piles up, worth a read if your storage room isn’t a static layout.
Condensate lines are the leak nobody budgets for #
Honestly, this is the one I’d flag above almost everything else. Storage rooms holding artwork or valuables usually run climate control, and climate control units produce condensate. That condensate runs down a line to a drain or a tray, and that line blocks, cracks, or the tray overflows. It’s slow, it’s quiet, and it’s directly above or beside the stock because that’s where the unit needed to go.
A sensor under the condensate line or tray, not just on the general floor, catches this early. Miss it and you get exactly the kind of slow, invisible water damage that ruins timber crates and frame backing boards weeks before anyone smells anything. This ties into the broader detection picture we cover on our fire and water detection page, and it’s worth comparing against how early-warning systems work generally, similar logic applies to how early-warning smoke detection differs from a standard smoke alarm in catching a problem before it’s obvious to a human walking past.
Sprinkler heads change where you need coverage, not whether you need it #
If the room has a fire sprinkler system, and under the National Construction Code many storage areas attached to commercial premises will, that’s an additional water source entirely separate from plumbing or weather. A sprinkler discharge, even a false trigger or a slow drip from a corroded head, needs its own consideration. I put sensors directly under sprinkler heads in these rooms as standard now, not as an extra. Too many clients think the sprinkler system and the leak detection system are unrelated problems. They’re not. One causes the exact event the other is meant to catch.
Wireless sensors and the walls people forget about #
A lot of older storage rooms, particularly ones retrofitted into existing buildings, have thick stone, brick or rendered masonry walls. That matters for wireless sensor signal, and we’ve gone into the specifics on why wireless sensors fail in old stone or brick gallery walls. For water sensors specifically, the risk is a sensor sitting in exactly the right spot physically, tucked under a rack against a stone wall, but reporting intermittently or not at all because the signal can’t get through to the panel. I’d rather run a wired sensor in a bad signal spot than trust a wireless unit and hope for the best. That’s not the popular view with some suppliers pushing wireless-everything, but it’s the one I’ll stand behind after enough jobs where wireless dropped out exactly when it mattered.
Object-level monitoring is a separate conversation but a related one, and if you’re weighing up sensor types generally our page on sensors and object monitoring covers where each type earns its place.
What Standards Australia and the Bureau of Meteorology actually tell you #
There’s no single Australian Standard that governs domestic or gallery water leak sensor placement the way, say, AS 1670 governs fire detection systems, so a lot of this comes down to trade judgement built from failures. Standards Australia’s published work in this space sits mostly in plumbing and building codes rather than detection technology specifically. What I do watch is rainfall intensity data. The Bureau of Meteorology’s records on short-duration heavy rainfall events are a decent reminder that storm water ingress isn’t a rare event in most of the country, it’s a when, not an if, for older buildings with ageing seals and downpipes.
The insurance question, and where I’ll stop #
Clients ask me constantly whether a missed water sensor placement will void a claim. I’m not a broker and ArtworkSecurity doesn’t sell or arrange insurance, so I won’t pretend to give legal advice here. What I will say plainly is that a security or detection shortfall doesn’t automatically mean a denied claim under Australian law, the Insurance Contracts Act requires the insurer to show the failure actually caused the specific loss, it’s not an automatic out for them. If you want the detail on how policies actually treat security conditions, that’s a conversation for your broker, and it’s covered properly on our security and your policy page.
What I can tell you, from crawling under enough racking with a torch, is that the sensor placement itself is rarely the expensive part of getting this right. The thinking beforehand is. Walk the room like the water will, not like the paperwork wants it to.
– Tom Reilly, Vault & Safe Editor