One spouse knows whom to call when there's a water leak. The other manages mother's medication and doctor appointments.

A couple assume their share of tasks until life intervenes and the better half — the one who knows what to do when the sprinkler is on the fritz — is suddenly gone on business or a family emergency or, worse, death.

Couples should be cross-trained in the affairs of life, experts say.

Such knowledge may even be the difference between life and death, says Donna Smallin, a professional organizer in the Phoenix area and author of several life-management books, including "Organizing Plain and Simple" (Storey Publishing, 2002).

If a spouse doesn't know the other's medications or medical conditions, or the same information for an aging parent, critical healthcare moments can be lost. And the spouse who has no idea whom to call when the minivan breaks down again must suffer through the hassle.

"Some of it's that people don't have time to discuss things," Smallin says. "But it's partly that, in relationships, people take on roles. It could be the man who typically handles finances or is in charge of when something needs to be done around the house, and then something happens and a woman doesn't know where the accounts are or other important information."

Basically, cross-training a spouse or educating an adult child on the whos, whats and wheres of your life comes down to compiling a list of phone numbers, passwords, account numbers and names. Three-ring binders designed to hold this information can be found online at sites such as www.Proorganizer.com and See www.JaneWork.com, and in books such as "Good Housekeeping: The Complete Household Organizer" (Hearst Books, 2006).

Notebook paper and an agreed-upon hiding place (you wouldn't want just anyone looking at your bank-account numbers) work fine, too.

Compiling and sharing such a notebook is an act of love, says Phoenix resident Pam Vozza, who has put together a notebook for her husband, Robert.

Vozza's notebook contains information about life-insurance policies, online accounts, her out-of-state family contact information, and a list of friends willing to baby-sit their 6-year-old daughter in an emergency. The notebook is broken into categories with tabs, and written in the simplest possible language.

"If anything ever happened to me, my husband would already be stressed out. I didn't want to stress him out even more," Vozza says.

The idea to compose such a book came from Vozza's observation of the working world. A state employee, Vozza watched longtime employees quit or leave "and take with them this whole body of knowledge." The organization suffered because of it. "If anything, God forbid, ever happened to me, my family would be in the doghouse because all this information was stored in my head," she says.

Nancy Nemitz, a professional organizer from Mesa, Ariz., grabbed a notebook and her husband of 32 years because she needed to record the practical workings of day-to-day living.

"I realized that if anything were to happen to him, people were going to ask me, 'Why, Nancy, you don't even know how to work your home after living there for 15 years?' "

Nemitz and her husband, Jeff, started at the outside of the house, checking out the workings of plumbing and how to operate the fish pond, and moved inside to cover the fuse boxes and how to operate the DVD. Moving from room to room is an effective way to learn the knowledge you're lacking. As a primer, couples might want to cross-train each other in electronics operation, plumbing issues such as how to set the sprinkler timer, and maintenance and operation of appliances.

"It was getting embarrassing, the things I did not know," Nemitz says. "But I finally took the bull by the horns, and it feels better."

AREAS IN WHICH SPOUSES SHOULD SHARE INFORMATION

HOUSEHOLD

Compile the company name, phone numbers, maintenance records and passwords necessary for the following: