ADU Plumbing Innovations: Space-Efficient Fixtures and Water-Saving Solutions

ADU Plumbing Innovations

If you’re building an accessory dwelling unit (ADU) or “granny flat” in San Diego, you’ll want to maximize space efficiency while keeping utility costs low. That’s where innovative ADU plumbing can help. When starting your ADU remodel or construction project, be sure to call ADU contractors in San Diego that specialize in smaller living spaces. They can help you select and install water-saving plumbing fixtures and make the most of your available square footage.Below are some of the latest space-saving water fixture trends for ADUs:

ADU Plumbing Innovations

Compact Toilets                         

Toilets are one of the main water-using fixtures that take up valuable floor space. New compact and wall-hung toilet designs are less than half the footprint of standard models. Popular options include:

  • Wall-hung toilets with concealed carriers – Installed higher on the wall, these toilets have a modern look with hidden plumbing hardware. Many meet the EPA’s WaterSense criteria for high efficiency using 1.28 gallons per flush (gpf) or less.
  • Short-projection toilets – With a rounded bowl design, these toilets extend less than 28” from the wall versus 31” for standard models. Short-projection bowls maximize space without sacrificing comfort.
  • Corner toilets – Perfect for small powder rooms, corner toilets wedge into room corners, leaving more floor area open. They have standard bowl sizes in a triangular footprint.

Water-Saving Sinks

sinks come in a variety of shapes and installations to save water and fit small ADUs:

  • Vessel sinks – These glass or metal bowls sit on top of the vanity surface, allowing for a smaller countertop. Many vessel sinks use less than 2.0 gallons per minute (gpm).
  • Pedestal sinks – Supported by a central pedestal base, these sinks don’t require any countertop or cabinet space. Look for low-flow models rated at 1.5 gpm or less.
  • Undermount sinks – Mounted below counter level, these sinks maximize counter space for small vanities and kitchenettes in ADUs. Undermount models as low as 1.0 gpm are available.
  • Corner sinks – Like corner toilets, these triangular sinks are an excellent bathroom problem solver in tight spaces. Corner sinks allow for a couple more precious inches of walking room in the loftiest of spaces.

In bathrooms and kitchens, faucets also contribute to an ADU’s overall water usage. The latest low-flow bath and kitchen faucets use less than 1.5 gpm while still providing adequate flow for washing and cooking tasks. Touchless faucets are also handy for keeping surfaces clean in compact ADUs.


Check showerhead ratings when selecting models for small or narrow stall showers in ADUs. The most efficient showerheads use no more than 1.75 gpm but still offer full-spray performance. New showerhead technology offers higher pressure with less water flow, an advantage in tiny shower stalls with limited elbow room.

Along with water-efficient fixtures, ADUs can also conserve water with drain recycling systems. So-called “greywater” systems collect drain water from showers, sinks, and washing machines to reuse for flushing toilets or landscape irrigation.

Multi-use Fixtures

For ultra-compact ADUs, combining the utility of plumbing fixtures allows for even more efficient use of limited space. Multi-use fixtures are a clever solution for tiny homes including ADUs under 500 square feet. Some space-saving combo fixture options are:

  • Wet baths – These bathroom spaces combine the shower, sink, and toilet areas into one water-tight room with proper floor drainage.
  • Shower/laundry combos – Installing a showerhead over your laundry area or washing machine lets you wash clothes and people in the same cubby.
  • Tap/utility sink combos – Installing your kitchenette or bathroom sink over your water heater makes use of air space while conveniently draining water heater discharge for reuse in the sink.

Careful selection of compact yet efficient plumbing fixtures and some creative layouts allow ADUs to feel light and spacious, rather than cramped. With innovations like wall-hung compact toilets, tiny corner sinks, and narrow shower stalls with low-flow heads, ADU baths and kitchens can be highly livable and water-wise. Connect with ADU pros when remodelling or building out your ADU to take advantage of every inch and gallon.