Your questions delve into complex legal areas that, in truth, deserve an experienced real estate attorney’s attention. I see multiple areas of liability that may concern you. Generally speaking, anyone who shares infrastructure in Colorado is responsible for sharing in the costs of fixing and maintaining it to the extent that it's proportional to each party’s ownership interests. C.R.S. 38-23-101 However, local ordinances can also apply to the shared water line situation. 

Herein lies the problem: You and your neighbor both have a vested interest in fixing the water line, but for different reasons. The leak that caused flooding in your crawl space could be legally recognized as continuous trespass, for which the court can hold responsible parties accountable. But determining who is responsible for improper installation may be difficult, considering the amount of time that has likely passed since the work was done. Even if you’re within the timeframe needed to sue for construction defect, it may be difficult to prove negligence. 

Meanwhile, your neighbor has been without water for weeks, a significant problem for which you could be held liable. While there may not be a direct legal duty to accommodate your neighbor, a court would almost certainly scrutinize what steps you took to mitigate or reduce your neighbor’s inconvenience. 

Now, about your tenants: If you're concerned about your liability as a landlord as it applies to your home’s leak, you have a duty to promptly address the issue if they bring it to your attention. If the leak is interfering with the health and safety of your tenant, then you could be expected to make reasonable accommodations, such as providing them with another place to stay while the repairs are made. I can see why you may be concerned if the tenant’s personal property has been damaged as a result, but you aren’t responsible for their renters’ insurance.

I recommend booking a consultation with one of our real estate attorneys about how you can reduce the liabilities you may face, should your neighbor choose to sue. Our Real Estate Team handles complex cases like yours and can help you negotiate with your neighbor and any other potential responsible parties. I hope this helps!