“leech” vs. “leach”

Use "leech" for the bloodsucking worm or a person who drains resources from others; use "leach" for substances gradually seeping or draining out through soil or material.

The real distinction

These are homophones for most speakers, though they come from related but distinct Old English roots and describe entirely different things today — one a parasitic worm or a draining person, the other a chemical or environmental process of gradual seepage. "Leech" is always a noun (or occasionally a verb meaning to persistently take from someone, as a leech would take blood), referring to the actual creature or a person exploiting others. "Leach" is always a verb describing substances gradually dissolving or seeping out of soil, rock, or material, common in environmental science and gardening writing (fertilizer leaching into a water table). If your sentence involves the bloodsucking worm or a parasitic person, use "leech"; if it involves chemicals or minerals seeping out through soil or filtration, use "leach." Medical history writing occasionally revisits "leech" therapy, once mainstream and now used narrowly in reconstructive surgery, while environmental science writing relies on "leach" to describe contamination processes in soil and groundwater. Gardeners also use "leach" when discussing how nutrients wash out of potting soil during heavy watering.

Examples with “leech”

• Doctors once used leeches to treat various ailments.
• A leech attached itself to the swimmer's ankle.
• He accused his freeloading roommate of being a leech.
• The pond was known for its population of leeches.
• She pulled the leech off carefully with tweezers.
• The parasite behaved like a leech, draining its host slowly.
• Modern medicine still occasionally uses leeches for microsurgery recovery.
• The con man leeched off his elderly relatives for years.
• The nature guide pointed out several leeches in the shallow water.
• He described his ex as an emotional leech who drained him.
• Surgeons still occasionally use leeches to reduce swelling after reattachment.
• The biology class examined a live leech under the microscope.
• He resented being treated like a leech by his in-laws.
• The pond's murky water hid dozens of leeches.
• He was fed up with his leech of a business partner.
• Divers spotted several leeches clinging to submerged logs.

Examples with “leach”

• Fertilizer can leach into nearby streams after heavy rain.
• Heavy metals slowly leached from the old pipes.
• Scientists studied how pesticides leach into groundwater.
• The soil test showed nutrients had leached away.
• Rainwater leached minerals out of the limestone cave.
• Chemicals from the landfill leached into the water table.
• Salt leached out of the soil after years of irrigation.
• The coffee grounds leached flavor into the cold water overnight.
• Overwatering caused nutrients to leach from the potted plants.
• Acid rain leaches minerals from rock over long periods.
• The report warned that toxins could leach from the old batteries.
• Runoff caused fertilizer to leach into the nearby pond.
• Years of rain leached the color from the old sign.
• Copper leached from the old pipes into the tap water.
• Nutrients leach faster from sandy soil than from clay.
• The report found pesticides had leached into the aquifer.

Memory trick

"Leech" has a double "e" like "creep," fitting for a creepy bloodsucking worm or a person who creeps into your wallet. "Leach" contains "each," and think of chemicals slipping out drop by drop, each one leaching away separately into the soil.