A smart doorbell will not save your house. A $15 water sensor under your water heater might. The devices worth buying share one trait: they detect a slow-moving disaster early enough that you can still do something about it. Here's what's worth installing, in the order we'd install it — and what every one of these devices does the moment your power and internet go down.
Comparing Your Options
Cost ranges below are our own editorial estimates for the product category, based on typical retail pricing. They are not quotes for any specific product — check the retailer for current pricing.
| Device | Typical Cost | Prevents | Works Without Power? | Priority |
|---|---|---|---|---|
| Water leak sensor | $15–$40 each | Slow leaks, tank failures | Local siren yes, alerts no | Buy first |
| Smart smoke / CO alarm | $40–$130 each | Fire, carbon monoxide | Yes — battery required | Buy first |
| Freeze / temp sensor | $20–$50 | Burst pipes | Local only | Cold climates |
| Automatic water shutoff | $400–$1,000 installed | Catastrophic flooding | Varies by model | High value, high cost |
| Smart thermostat | $100–$250 | Freeze damage while away | No | Worthwhile |
| Sump pump monitor | $50–$200 | Basement flooding | Battery models only | If you have a sump |
| Cellular-backup camera | $100–$300 + fee | Post-evacuation blind spots | Yes, with LTE backup | Optional |
| Smart doorbell / lock | $100–$350 | Convenience only | No | Skip for protection |
What to Look For, Category by Category
1. Water Leak & Freeze Detection
Water is the peril most likely to damage your home and the one smart sensors handle best. A failing water heater, a cracked supply line behind a washing machine, or a slow leak under a sink can run for days before anyone notices. A sensor turns that into a same-hour problem.
What to look for
- A loud local siren, not just an app alert. If the hub is down or your phone is on silent, the siren is what saves you. Look for 90dB or better.
- A replaceable, long-life battery with low-battery warnings — these sit forgotten for years.
- A probe or cable extension for pans and tight spaces behind appliances.
- Built-in temperature reporting, so one device covers both leak and freeze risk.
- Multi-packs. Coverage matters more than features. Six cheap sensors beat one expensive one.
Where to place them
- Under and beside the water heater — the single highest-value spot
- Behind the washing machine, at the floor
- Under kitchen and bathroom sinks
- Beside the sump pit, above the normal water line
- At the base of the furnace or air handler (condensate overflow)
- Near any supply line running through an unheated space
Automatic water shutoff valves
A shutoff valve installs on your main line and closes it when it detects an abnormal flow pattern or a signal from a paired leak sensor. This is the difference between a wet floor and a destroyed first floor, and it's the only device here that acts rather than alerts. Expect $400–$1,000 including professional installation, and check whether your insurer offers a premium discount — several do, which changes the math considerably. Confirm the model holds its position or fails closed during a power outage before you buy.
2. Smart Smoke & CO Alarms
Interconnection is the real feature here. When a basement alarm sounds, every alarm in the house sounds — that's what wakes people upstairs. Smart models add a phone alert when nobody is home, which matters if a fire starts while you're at work.
What to look for
- Combination smoke + CO in one unit, so you aren't managing two device types on two schedules.
- Both photoelectric and ionization sensing (often sold as "dual sensor") — they detect smoldering and flaming fires respectively.
- Interconnection, wired or wireless, across every level.
- A 10-year sealed battery or hardwired power with battery backup. NFPA recommends replacing smoke alarms 10 years from the manufacture date printed on the unit — not from when you installed it.
- Local alarm independent of the cloud. The siren must work with the internet down. Verify this, don't assume it.
3. Power & Outage Monitoring
If you're away when the power fails, you want to know — a dead sump pump during a rainstorm or a thawing freezer are both problems with a clock on them.
What to look for
- Sump pump monitors with their own battery and a high-water float, so they alarm on both power loss and pump failure. A pump that's running but not keeping up is the failure mode people miss.
- Smart plugs with energy monitoring on the freezer and sump — an unexpected drop to zero watts tells you something died.
- A small UPS for your router and modem. This is the piece nearly everyone skips. Without it, every Wi-Fi device in your house goes silent the instant the power fails, which is exactly when you need them talking.
- Generator monitoring, if you have a standby unit — most manufacturers offer a Wi-Fi module that reports exercise cycles and fault codes.
For sizing a generator to run these circuits, see our generator buying guide and the wattage breakdown in the backup power guide.
4. Climate & Structural Monitoring
These are lower priority than water and fire, but they close real gaps — especially for second homes, rentals, and anyone who travels during winter.
What to look for
- Smart thermostats with a low-temperature alert and a hard minimum setpoint. The alert is the point; remote control is a bonus.
- Standalone temperature and humidity sensors for crawlspaces, attics, and unheated garages where pipes run.
- Smart garage door controllers with an open-state alert. An open garage door during high wind is a structural risk, not just a security one — see the wind-load discussion in our hurricane guide.
- Indoor air quality monitors with PM2.5 if you're in wildfire country. They tell you when to close up and run filtration — pair with the guidance in our wildfire guide.
5. Cameras — Useful, With Caveats
A camera doesn't prevent damage. What it does is let you see your property after you evacuate and before you're allowed back, and give you timestamped footage for an insurance claim. That's a genuine benefit, but be clear-eyed that it's documentation, not protection.
What to look for
- Cellular (LTE) backup. A camera on home Wi-Fi is useless in exactly the scenario you bought it for. Without cellular fallback, the feed dies with your internet.
- Local storage on an SD card in addition to cloud, so footage survives a connectivity loss.
- Battery or solar power for at least one exterior camera.
- An honest look at the subscription cost — most of these carry a monthly fee that exceeds the hardware price within two years.
What Every One of These Devices Does in a Real Storm
This is the section most smart home guides leave out. Nearly every device above depends on two things that fail early in a severe weather event: household power and internet service. When both are gone, a cloud-dependent sensor is an inert piece of plastic.
- Wi-Fi sensors stop sending alerts the moment your router loses power — the sensor may have battery, but the network doesn't
- Cloud-only devices stay dark even if your power is fine but your ISP is down
- Hub-based systems fail entirely if the hub is unpowered — one point of failure for every sensor
- Cameras without LTE backup record nothing you can see remotely
- Smart locks and thermostats generally revert to their last state with no notification
How to build around it
- Put your router and modem on a small UPS. Cheapest, highest-leverage fix on this page — it keeps your entire sensor network alive through short outages and gives you a working alert path during longer ones.
- Prefer devices with a loud local siren that fires independently of any network.
- Prefer local control or local storage over cloud-only designs wherever the option exists.
- Test the failure case deliberately. Unplug your router, trip a sensor, and see what actually happens. Do this once a year, in the same session you test your smoke alarms.
- Don't let sensors replace physical measures. A freeze sensor is not pipe insulation. A leak sensor is not a shutoff valve. Sensors buy you time; hardware prevents the damage.
A Sensible Order to Buy In
- Water leak sensors, multi-pack. Under $50 covers the six highest-risk spots in most homes.
- Combination smoke + CO alarms on every level, interconnected, with sealed 10-year batteries.
- A UPS for the router and modem. Makes everything above and below it actually work when it counts.
- Freeze and temperature sensors in unheated spaces, if you're anywhere with a real winter.
- A sump pump monitor, if you have a sump pit.
- A smart thermostat with low-temperature alerting, especially for a home you leave empty.
- An automatic water shutoff valve, once the cheap layers are in place — and ask your insurer about a discount first.
- Cameras with cellular backup, last, and only if remote visibility genuinely matters to you.
Free Home Monitoring Checklist
Sensor placement map, an annual test routine, and the outage-resilience checklist from Part 3 — in one download.