Re: missing clothes. If she went into the tank voluntarily, she probably would have removed her clothes first so she wouldn't be a sopping mess afterwards. That tank is right on the edge of the building and, 15 stories up during winter, it was probably windy. If her clothes were blown away, they're long gone. A homeless person probably picked them up off the street.
I keep wanting to give LE the benefit of the doubt and trust that they really think it was most likely an accident. That being said, I've been trying to figure out how this could happen accidentally, and be somewhat obvious as an accident, since it doesn't seem to have raised many red flags with LE. So, if I'm a young woman traveling alone, what am I doing on the roof? Probably checking out the view, maybe taking pictures to share online. Personally, I'm not sure I'd ever hang out on top of a water tank, but I might want to reach the hotel's highest peak, which would be that room next to the tanks. I'd probably eventually sit on a ledge to take in the view.
The ONLY thing that would get me inside a tank is if something extremely important fell into that open hatch. Considering there's still no lid, and the Cecil is one of the nastiest, irresponsible hotels I've ever heard of, I don't doubt that tank never had a lid.
Perhaps while she sat on the ledge above the tanks, she dropped her camera? Or her phone? If it was something important enough, is it possible she (being alone) decided to undress and jump in and out as quickly as possible to retrieve the item?
While in the tank (diving for the item), the pipes may have started suctioning and caught her by the hair, drowning her. If LE finds her head down, feet up, with her hair stuck in the pipe, AND with water in her lungs, that definitely looks like an accidental drowning, not a murder.
I'm sure it had a lid. The other 3 had lids, so why not this one - the main tank. I wouldn't be surprised if someone had decided to take a leak or a dump inside one of those water tanks either.
If it was open already, and she somehow dropped something valuable inside, going into a tank with no visible way out is not something anybody would do. It's an extremely unlikely scenario that her clothes blew off down the street. Also, where is her room key/card?
If the police do decide it is an accidental death, I hope they reveal their evidence publicly for scrutiny.