DIY & safety

What you should never DIY

This isn't about gatekeeping. These categories of work carry consequences that are disproportionate to what you'd save: contamination, fire, flooding into structure, or a repair that fails an inspection later.

Anything involving gas

Gas lines, gas appliance connections, and gas water heater combustion components are regulated work in virtually every jurisdiction. The failure modes are fire, explosion, and carbon monoxide.

Moving, extending, or capping a gas line
Reconnecting a gas appliance after work
Adjusting burners, gas valves, or venting

Sewage and main drain lines

Sewage carries pathogens, and main line work usually needs proper equipment, cleanouts, and sometimes camera inspection. Powered drain machines can injure badly and can damage older pipe.

Clearing a main sewer line with rented powered equipment
Cleaning up significant sewage contamination yourself
Opening, cutting, or rerouting a buried drain line

Water heaters

Tanks combine mains pressure, very hot water, and either gas combustion or high-current electrical supply. Temperature and pressure relief valves exist because failures here are violent.

Replacing a tank or tankless unit
Replacing a temperature and pressure relief valve
Raising the thermostat above a safe setting or bypassing a safety control
Working on heating elements without isolating and verifying the supply

Main water supply and concealed pipework

A mistake on a pressurized main or inside a wall isn't a drip — it's a flood into structure you can't see, and often a permit issue when it's discovered later.

Cutting into main supply lines or the service line from the street
Soldering, brazing, or press-fitting inside walls, ceilings, or floors
Repiping, relocating fixtures, or altering drain venting
Anything involving the backflow preventer or the water meter assembly

Work requiring a permit or inspection

Rules vary by state and locality, but new or relocated fixtures, repiping, water heater replacement, and drain alterations commonly require a permit. Unpermitted work can complicate insurance claims and property sales.

Adding or relocating a fixture
Altering drain, waste, or vent piping
Any work a local inspector would expect to sign off

Chemical and tool hazards

Some 'quick fixes' cause more damage than the original fault.

Repeated use of caustic drain chemicals, which can damage pipe and create a hazard for whoever opens the line next
Mixing drain products, which can release dangerous gases
Over-tightening fittings on old pipe, which can crack them
Using a torch near framing, insulation, or anything concealed

What regulation actually requires varies

There is no single national rulebook. Licensing sits with states, and permits are often issued locally, so the exact line between "homeowner may do this" and "licensed work only" moves depending on where you live — in some places a homeowner may perform certain work in their own residence under permit, and in others they may not. Check with your local building department before assuming.