If I wanted a backyard guest house, how deep would my pockets need to be?

Really appreciate your honesty here. It’s so true - those early utility decisions can make or break the whole project. I’ve seen clients regret not future-proofing, especially when it comes to rentals or resale. Your breakdown is spot on. It’s a pain upfront, but worth it later.

Honestly, future-proofing utilities is one of those things people groan about at first, but later it’s a lifesaver. I’ve had clients who tried to save by skipping proper plumbing runs or electrical capacity - regrets all around. Did you already decide if you’re pulling new lines or tapping into existing? That’s usually where costs start to snowball.

I get where you’re coming from about future-proofing, but I’d actually push back a bit on the “always pull new lines” approach. There’s a middle ground that can save money and still keep things green and efficient. For example, if your existing electrical panel has enough capacity, you can often run a subpanel to the guest house instead of a whole new service - less copper, less trenching, less waste. Same goes for water: sometimes a branch off the main with proper backflow prevention is all you need.

I’ve seen people go overboard with “future-proofing” and end up with oversized systems that just sit there unused. It’s worth doing a load calculation and thinking through what you’ll actually need. If you’re planning for solar or EV charging later, sure, size up - but otherwise, sometimes simpler is better. Overbuilding can be just as much of a headache as underbuilding, especially if you’re trying to keep the project eco-friendly and within budget.

I get what you’re saying about not overdoing it. I’ve seen people run massive conduit “just in case” and then regret the cost.

“sometimes a branch off the main with proper backflow prevention is all you need.”

I hear you on the “just in case” syndrome. When we redid the plumbing in our 1920s place, the contractor tried to sell me on pipes big enough to irrigate a golf course. I told him, “Buddy, I’m just trying to keep my tomatoes alive, not run a water park.” Ended up saving a chunk by sticking to what we actually needed. Honestly, I’d rather splurge on storm windows than bury a fortune in the backyard for future mystery projects.