Homemade Gray Water Kitchen Drain

Garden or Flowerbed Needs

• Determine your household gray water demand by measuring the length and width of your garden or flowerbed. Cross reference rainfall tables and native locations of your plant species to determine the amount of water your plants need to survive. The difference between your region's rainfall and the plant's native region's rainfall, measured in inches of rain per month, multiplied by the area of your flowerbed determines the area's yearly non-rainfall watering demand in inches. Calculate the supply based on your frequency of dishwashing and kitchen sink use and the result, in gallons, equals your minimum storage requirements.

Sink Drain Work

• Observe and trace the path between your proposed reservoir and the existing kitchen sink. Document and measure all obstructions, structures and supports that lie between the gray water source and its destination. Consult with a plumber and carpenter or general contractor for a second opinion, if necessary, to determine the most practical route. Prepare a shopping list based on your measurements and site conditions. Include elbows, check valves, appropriate sealants and hardware to secure and install plumbing in your list.

Plumbing the Drain

• Turn off all water to the sink to prevent spills from interfering with your work. Use an appropriate wrench to disconnect the drain tube from the waste line. Retain the fittings and the P-trap for reconnecting to the new waste line. Cap the exposed opening where the drain tube was disconnected to prevent spills from other waste water. Prepare to install your new waste line by drilling an appropriate-size hole if necessary. Reconnect the P-trap to the new drain line and secure and slope the drain line according to local plumbing code requirements. A sloped drain prevents standing or stagnant water and resulting biohazards. For a quicker installation, consider PVC in place of copper pipes.

Connect to the Reservoir

• At the low point, the destination for your gray water, clear the ground to prepare for your storage tank. Level and fill the storage tank base area to fit your tank. Install a mesh or screen at the inlet of your storage tank to prevent wildlife or plant clogs. Verify with measurements that the drain outlet is the lowest point in your plumbing and the highest point in your reservoir. A modified, plastic 55-gallon drum makes an appropriate reservoir in most installations. To maintain hydraulic pressure -- water pressure -- install the reservoir with as much height as is practical. If this is not possible, install a self-priming water pump to push water up a hose to the garden.