Plumbing Design Ideas: The Choices Worth Making Deliberately

Plumbing is invisible until it fails, which is why it gets decided by default. During a remodel you get one cheap opportunity to make choices that otherwise cost a fortune, and most people spend it thinking about faucet finishes.

Green Design and Build (CSLB #1110975), a licensed general contractor in Van Nuys, manages the plumbing inside its remodels, ADUs and additions across Southern California. A whole-house repipe of a 2 to 3 bathroom home typically costs $8,000 to $25,000 in Los Angeles. For the work itself and the other plumbing figures, see plumbing.

The layout question: how far can a fixture move?

Water can go almost anywhere. Drainage cannot — it runs downhill at a required fall, and it needs venting. That is why moving a sink is usually simple and moving a toilet is usually not.

• Sinks move relatively easily.
• Showers and tubs depend on where the drain can fall to.
• Toilets are the least forgiving fixture in the house.
• Anything on a slab multiplies the cost, because relocating a drain means cutting concrete.

This is why we ask where the existing lines run before a layout is settled. Moving a fixture on paper is free; moving it after the slab is cut is not.

Repipe while the walls are open, or not at all

If the house has galvanized steel supply pipes, they are corroding from the inside and the question is when, not whether. Repiping during a remodel, while walls are already open, costs a fraction of doing it as its own job with all the patching, drywall and repainting that involves.

This is the single clearest example of the principle behind all these pages: the work is not expensive, the access is. If you are opening walls anyway and the pipework is old, do it now.

Water heating, which is a bigger decision than it looks

• Conventional tank. Cheapest to install, takes floor space, finite hot water.
• Tankless. Endless hot water, takes no floor space, needs a larger gas supply or a substantial electrical circuit, and often a new flue. Retrofitting into a house not set up for it is where the cost sits.
• Heat pump water heater. Efficient, needs space and air movement around it, and a dedicated circuit.
• Recirculation. Hot water arrives quickly rather than after a minute of running the faucet. Cheap to add during a remodel, disproportionately noticeable every day.

Pressure, and why the shower disappoints

A shower that underwhelms is usually not the fixture. It is pipe size, an old pressure regulator, or too many fittings served by one undersized line. Replacing a showerhead to fix low flow rarely works. Establishing the actual cause before you buy fixtures saves money and disappointment.

Small decisions with permanent effects

• Shut-off valves at every fixture. Trivial during installation; the difference between a small leak and a flooded house.
• A whole-house shut-off you can actually reach.
• Access panels where anything might need service later.
• Insulating hot lines in walls and under floors.
• A stub and shut-off for a future hose bib, ice maker or bidet.

The requirement that catches people out

California Civil Code section 1101.4 requires that when a permit is issued for an alteration or improvement to a single-family home, every non-compliant plumbing fixture in the house is replaced with a water-conserving one as a condition of final permit approval — even fixtures nowhere near the work. How strictly the building department checks varies by city, so budget for it rather than discovering it at final inspection.

Sources: California SB 407 (2009), Civil Code sections 1101.1–1101.8 (the statute behind the whole-house fixture retrofit).

What costs more than people expect

• Relocating drainage, especially on a slab.
• Tankless conversion in a house not already set up for it.
• Whole-house fixture retrofits triggered by a permit.
• Opening finished surfaces to reach pipework.

What is cheaper than people expect

• Repiping while walls are already open.
• Recirculation added during a remodel.
• Fixture shut-offs and access panels.
• Stubs for future fixtures.

Questions we get asked

Why is moving a toilet so expensive?

Because drainage runs downhill at a required fall and has to be vented, unlike water supply which can go almost anywhere. On a slab, relocating a toilet drain means cutting concrete. Sinks move easily; toilets are the least forgiving fixture in the house.

Should I repipe during my remodel?

If the house has galvanized steel supply pipes, yes. They corrode from the inside and will eventually need replacing. Doing it while walls are already open costs a fraction of doing it later as its own job with all the patching, drywall and repainting that involves.

Is a tankless water heater worth it?

It gives endless hot water and takes no floor space. The cost sits in retrofitting — it usually needs a larger gas supply or a substantial electrical circuit and often a new flue. In a house already set up for it, straightforward; in one that is not, it is a real project.

My water pressure is poor. Will a new showerhead fix it?

Rarely. It is usually pipe size, an old pressure regulator, or too many fixtures on one undersized line. Diagnosing the actual cause before buying fixtures saves both money and disappointment.

What is hot water recirculation?

A system that keeps hot water near the fixtures so it arrives in seconds rather than after a minute of running the faucet. It is cheap to add during a remodel and one of the things homeowners notice most afterwards.

Why might a permit force me to change fixtures elsewhere in the house?

Because California Civil Code section 1101.4 makes replacement of all non-compliant plumbing fixtures in a single-family home a condition of final permit approval for any alteration or improvement, whether or not those fixtures are in the scope of work.

Related: All design ideas · Plumbing · Bathroom design ideas · Kitchen design ideas · Whole-home renovation ideas

Tell us about your plumbing project

Send us the basics — what needs replacing or moving, the age of the house, and roughly when you would like to start — and we will come out, take measurements and put a written scope and estimate in front of you within about 48 hours of the visit.