Over the next few weeks, Procter & Gamble plans to introduce easier-to-read plastic measuring caps for its liquid detergent brands, including Tide, Gain, Era and Cheer. The new caps will have more-defined measurement lines inside and bigger numbers that are staggered, not stacked, says Dawn French, P&G’s head of laundry research and development for North America.

Why?  Because, according to the Wall Street Journal, Americans use too much detergent per load.  They have come to think that more soap equals cleaner clothes, which is not the case – rather it causes build-up and dingy colors.  Additionally,  more consumers are buying high-efficiency washers which need even less of today’s concentrated detergents.

Packaging, in most cases, hasn’t helped. The molded lines and numbers inside detergent caps are hard to read, especially in a dimly lit laundry room. And even though concentrated detergents have been on the market since at least 2007, many caps still hold more than is needed for an average load.

Method Products Inc. this month launched an ad blitz for a new detergent with a pump dispenser, designed to help curb overdosing. Method found that 53% of people don’t use the recommended amount of detergent per washload, preferring instead to guess or, worse, to simply fill the cap up to the top—a practice that wastes more than half the loads a detergent bottle could wash, Method executives say.

Through much of Europe, detergent premeasured in tablets and sachets has been popular for years. But in the U.S., pre-dosed products have been largely unsuccessful. Consumers usually pick up their laundry habits during adolescence from their mothers, and changing them is hard, says Bob Deutsch, founder of Brain Sells, a marketing consulting firm.

American consumers, it seems, also want more control. Many people have their own laundry “recipe,” and each one believes her unique method leads to superior results, industry executives say. P&G, the world’s leading detergent maker, calls such involved laundry doers “master chemists.”

General Electric Co.’s top-of-the-line Profile frontload washer offers to take on all dosing decisions itself. The SmartDispense feature, adding $600 to the cost of the machine, holds up to six months’ worth of detergent and allocates the right amount for each load, taking the detergent concentration level and the amount of clothes into account.

Proper dosing is the biggest laundry concern among callers to Seventh Generation Inc.’s help line, says Sue Holden, head of the consumer-insights team at the Burlington, Vt., household-product maker. Two years ago, the company started making its detergent bottle cap with translucent plastic partly to make it easier to read. “We’re trying to train people to do something that doesn’t come naturally,” says Ms. Holden. “Growing up, a lot of us just poured it in.”

Seventh Generation’s co-founder, Jeffrey Hollender, wonders why more people haven’t stumbled upon laundry’s big, dirty secret: “You don’t even need soap to wash most loads,” he says.  The agitation of washing machines often does the job on its own.