As an onsite system installer, you can predict when you might get complaints about your craftsmanship … and hear a few choice words from a customer whose system isn’t working to its full potential.

The first opportunity is probably right after the new or replacement system is brought online. There may be a glitch or two and you might be called out to tweak the operations to get it working optimally.

Another occasion for raising the ire of customers is a year or two into system use, after overloading or abuse has taken its toll. Then it’s time to reassure the end-user about the system’s design capabilities and ask if water usage has changed dramatically of late … maybe triggered by a teenager taking skin-pruning showers every morning.

If they’re calling in December, it’s not likely to pass along their holiday cheer! Rather, it could be a befuddled homeowner, like the character Clark Griswold, from National Lampoon’s Christmas Vacation, calling because the toilet isn’t flushing so well anymore … and that his 27 visiting relatives need to use the bathroom.

What would Miss Manners do?

It is with this image in mind that I was so interested in a recent column by Rick Meade in Maine’s Portland Press Herald. Meade wrestled with the notion of warning city dwellers visiting his country home to go easy on his well and septic system lest he suffer an expensive failure. He rightfully noted that people used to the blissfully endless flow of a municipal water and sewer system wouldn’t give a thought to water conservation when they stay at his house for extended periods.

“Day in and day out, they use gallons and gallons of water, then it just disappears with nary a concern. … Understandably, they’ve been brought up oblivious to the link between supply and demand; the ability to deliver and capacity to remove,’’ he wrote. “Seriously, when visitors arrive, how can we broach the topic of our septic functions in a way that is clear, descriptive and undeniable but not off-putting? ‘Pass the potato salad please, and that reminds me, did I ever explain how our septic system operates?’ ”

Meade’s is no doubt a conundrum faced by millions of septic system users across the country this time of year. These people are your customers, those for whom you designed and installed an onsite system, or those who trust you to inspect and maintain functioning systems. It seems to me that part of the maintenance program is giving customers ideas on how to educate their holiday guests who are uninformed on the proper use of septic systems.

So how about a few pointers to ensure customers don’t invite you to their next holiday gathering? Here are a few, and feel free to send your ideas to add to the list for next year.

Provide house rules

In his column, Meade dismissed the idea of posting a sign in the bathroom to announce water usage rules. I say, “Not so fast, Rick!’’ When it comes to protecting your septic system, I think clearly stated rules are in order. Would the list include the old saying, “If it’s yellow, let it mellow’’? Maybe you don’t want to put it in those terms, but you can encourage visitors to limit their flushing. Let them know it’s not OK to leave the water running while shaving or brushing teeth. Explain that only toilet paper and bodily wastes get flushed, and not wipes or chemical cleaners or unused medicines that may harm the onsite system.

Put a timer in the shower

If the extended family is coming for a week, it’s OK to sit them down and explain the loading limits of a septic system. If eyes glaze over and it doesn’t seem like the information is registering, tell visitors there’s a kitchen timer in the bathroom and they should set it for five minutes before stepping into the shower. If they balk, paint a verbal picture about what conditions will be like when the tank overloads and nobody will be able to use the bathrooms for a few hours or days.

Hit the laundromat

If guests stay long enough to require clothes washing, you might think they’ve worn out their welcome. But we love our family and friends and enjoy their company for extended periods, right? Encourage them to combine their dirty laundry with yours to make full loads and to do the laundry when other water usage in the house will be low. Or when the dirty clothes pile up, announce that everyone is taking a field trip. Make an afternoon of driving to the nearest laundromat and popping a sack of quarters into a few of those giant-capacity machines. This will take a lot of pressure off of an onsite system.

Watch the dirty dishes

Holiday meals can leave a big mess in the kitchen. Serve a big enough crowd and you’ll use all your dishes and utensils. Tell customers to do what they can to stagger dishwashing or come up with other ideas to slow the flow down the kitchen sink. Some dishwashers have special “eco cycles” that use less water, or delay timers so dishes can be washed in the middle of the night when there’s little other water usage. How about going out to dinner a few times? Let the restaurant clean up after the crowd. Or put away the silver and fine china. Every meal doesn’t have to be the way grandma made it back in the day. It’s surprising how little water is used when you bring home a bucket of chicken and a pizza.

Provide a portable restroom

Do you live in Florida or Arizona? Lucky for you; no snow to shovel. In your temperate climate, septic owners could rent a portable restroom for the backyard and have outdoor party guests use that instead of bathrooms in the house. Because portable restrooms don’t use as much water as a toilet, this could be promoted as a “green’’ alternative and every time a guest makes that choice, they’re helping the environment.

A serious message

Am I joking around with some of these suggestions? Sure. But there is a serious message to convey. You are an onsite system professional, and it’s important for you to clearly explain the operating limitations of systems to your customers. While some homeowners listen to you and educate themselves about how to properly use their systems, many do not. And you are providing a service by reminding them that systems are especially vulnerable to overuse this time of year. If you save one joyous family reunion from turning into a septic disaster, these reminders have made a difference.