Original toilet in a 50 year old house has developed about a five inch horizontal hairline crack on the side which is leaking even though it is visible on the only on the outside, not inside. I'm assuming that a crack can not be effectively sealed and I will have to replace the toilet. However, someone suggested that the lower amounts of water used in the new toilets may be insufficient to carry waste through the pipes which may have narrowed with corrosion over the years.
IF this is true, what options are available to ensure that problems don't arise when a new toilet is installed?
Thanks.