I respond by showing them to the nearest bathroom. 

Let's see if the water is on.  Go for it.

If the listing agent is present, I ask. If not, I check out the bathroom to verify if the water is working. There is not much more you can do, other than verify afterwards that they flushed.

I make sure the water is on if it is a vacant house! If that is set it's ok with me.

As long as the water is not cut off, I tell them it is accceptable.

In an unoccupied property, I first check to make the water is on and then give the okay.  I keep a roll of toilet paper in my realtor supply kit in my trunk in case there's none in the property.

I say no.  Worst case scenarios do happen - & I don't want to be the one explaining it to the listing agent.  

Sometimes there are no other options that meet the urgent needs.

However, it is a good idea to check the bathroom before leaving the property.

I make sure there is TP, or no go. 

Susan nailed this one!

Sure I let them.  If the seller has a problem they must state it.

Reminds me of a joke my Dad used to tell Jack. It depends on your estimation of how serious, or not, this Buyer seems to be. 

Yes, unless the water is turned off.

Hi Jack -- an important question.

-Make sure the water is on.

-Toilet paper

-Lid down after using.

I ask them to check if there is water service in the bathroom and if there is water it is ok.

Jack,

As a buyer, I have asked, and the agent said, yes.  The last thing you want is someone uncomfortable. A