By adding drain/fill ports before you build it..... After that, you can use Mayhem Blitz Kit (part 2 onlyfor refill I believe but someone can correct me if I'm wrong) or I use promochill sysreboot. Just make sure you flush with plenty of distilled after.

There's 3 basic types of liquid cooling. The most common is the AIO or CLC which is a closed loop cooler / all in one. That kind has zero maintenance other than dusting like normal. Lasts @ 5 years before things go downhill, and when that happens you just replace the whole thing. Since ppl usually don't keep a pc longer than 5 years, it's not a likely issue. Second most common is full custom loop. That's the massive tubing wrapping around everything kind of loop that you build yourself. It's an open loop, so does require periodic replacement, flushing of fluids, leak checking etc. Also by far the most expensive, but being open loop it's totally customizable to any configuration of cpu or gpu or radiator or pump setup you choose. Last is the hybrids. Fractal design, Swiftec and a few others have taken an AIO and outfitted it with standard custom loop fittings. This allows access to the coolant, so as long as the pump is still good, you can flush and refill or topoff the fluid as many times as you like or need to, far extending the usable 5 year time period of a standard AIO. It also means you can add a component, like a gpu, if you so choose to, just buy the normal full custom water block and plug it in. Most of the companies branding the hybrids also sell the correct fluid, so sticking with a particular brand is somewhat important unless you totally swap out the fluid. As far as the hybrids go, they are really nothing more than a common AIO mostly, they don't leak anymore than an AIO does, so fluids don't need to be checked. They just have that ability if you choose to. As for insurance, that's company specific. Corsair brands the most popular series of AIO's world-wide, and has been known for fact to have replaced entire pc's after a disaterous leak by their product. Whether that's true of any other company, I can't say as I've not heard of it, but then again, leaks like that are exponentially rare, and YouTube isn't that old, and not many brag about full system replacements and happy happy joy joy. You only see comments handed down by clueless ppl or videos about the damage caused by the piece of junk. AIO's/hybrids are warranty items in that if there is any leak anywhere it's usually replaced. Full custom loops are individual warranty items, if a rad springs a leak or a pump, it's covered, but not anything you do like a fitting leaking at the hose etc.