Tech arrived at a 45 service call. Upon arrival the customer mentioned water problems. The 90 percent flue pipe has water in it. The horizontal run was not sloped properly and was holding water. This was inhibiting the furnace draft components from functioning. The pipe was realigned and the drains were flushed. Management was contacted. The water is assumed to be from the previous appointment. The customer will monitor the water spots. The system was functioning upon departure.