Sewer lateral & water heater: how to tell how old yours is and when it fails

Q: How long does a water heater last?

Tank (gas or electric): 8–15 years. Tankless: 15–20 years. After about year 10, a tank water heater is on borrowed time.

Q: What are the warning signs a water heater is failing?

Rusty or discolored hot water, rumbling or popping sounds, water pooling around the base, or hot water running out faster than before. Standing water means replace now.

Q: How long does a sewer lateral last?

Clay (older homes): 50–60 years. Cast iron: 50–75 years. PVC (modern): 100+ years. If your house predates 1980, assume clay or cast iron in the back half of its life.

Q: What are the warning signs of a failing sewer lateral?

Repeated drain backups across multiple fixtures, gurgling toilets, sewage smell in the yard, or unusually lush patches of lawn over the line.

Q: What does sewer lateral replacement cost?

Spot repair: $1,500–$4,000. Full replacement (trenchless or dug): $5,000–$20,000+ depending on length, depth, and access.

These two are the quiet ones. A water heater and a sewer lateral both sit out of sight, both fail without much warning, and both turn into water-on-the-floor emergencies the day they go. The good news: each one tells you its age if you know where to look.

How long does a water heater last?

Tank (gas or electric): 8–15 years.
Tankless: 15–20 years.
Sediment, hard water, and skipped flushing all shorten it.

After about year 10, a tank water heater is on borrowed time.

How do I tell how old my water heater is?

Read the serial number on the unit's label. Most manufacturers encode the date there — often the first letters/digits map to month and year (the format varies by brand; a quick search for "[brand] water heater serial number age" decodes it). If it's unreadable, the home's records and install permits are a good proxy — and Almwell estimates it from property data automatically.

What are the warning signs a water heater is failing?

Rusty or discolored hot water.
Rumbling or popping sounds (sediment).
Water pooling around the base.
Hot water that runs out faster than it used to.

Any standing water means replace now, not later. A tank that lets go can dump 40+ gallons onto the floor.

What does a water heater cost to replace in 2026?

Tank: $1,200–$3,500 installed.
Tankless: $3,000–$6,000 installed (more if you're converting from a tank).

How long does a sewer lateral last?

The sewer lateral is the pipe carrying waste from your house to the city main — and it's the homeowner's responsibility, not the city's, which surprises people.

Clay (older homes): 50–60 years.
Cast iron: 50–75 years.
PVC (modern): 100+ years.

If your house predates about 1980, assume clay or cast iron and assume it's in the back half of its life.

What are the warning signs of a failing sewer lateral?

Repeated drain backups across multiple fixtures.
Gurgling toilets, slow drains everywhere at once.
Sewage smell in the yard, or unusually lush patches of lawn over the line.
Tree roots in the line (a camera inspection confirms it).

What does sewer lateral replacement cost?

Spot repair: $1,500–$4,000.
Full replacement (trenchless or dug): $5,000–$20,000+ depending on length, depth, and access.

This is the kind of five-figure surprise that the 1–3% maintenance budget exists to absorb. Knowing your home's age tells you whether it's a someday problem or a this-decade one. See our methodology for how Almwell estimates system ages. Also worth reading: HVAC replacement cost in 2026.