Plumbing systems are designed to allow the proper drainage of water out of a building to the county and city water treatment systems. There are two types of water draining systems in most buildings – storm water and wastewater. Wastewater systems contain sewer gases and storm water systems do not. A wastewater system is designed to vent sewer gases to the outdoors through a pipe, which passes through the roof. This same pipe also allows air to enter the system when water is draining.
Both storm and waste piping systems operate like a drinking straw. If you place your thumb over the drinking straw when water is in the straw, the water will not leave the straw. Air must flow in, before water can drain out. The weight of the wastewater leaving the building, will find air even if it has to pull air through plumbing fixture traps, causing a gurgling noise.
When a plumbing fixture drains, the wastewater first passes through the trap. The trap is a “U” – shape pipe that holds water sufficient to prevent sewer gas from entering the building. At the outlet of the trap is a tee in the pipe, which points up and down. Wastewater flows down and out of the building by gravity. Air is pulled in through the pipe connected to the up side of the tee at the trap. A storm drain system does not contain a trap and cannot to be connected to any system, which does contain a trap. This is how your plumbing system works in a very basic and broad sense.
Should you experience any of the warning signs first discussed above, your drain system is failing to do its job. Your first step to understanding drain failure issues should be contacting a local mechanical consultant to evaluate the global condition of the piping. Consultants design a systematic approach to finding a fact-supported conclusion. Contractors make repairs, but should not be relied upon to give an expert opinion, which can result in thousands to millions of dollars in repairs.
A proper assessment of the cast iron pipe condition will require looking at sections of pipe. Some sections of cast iron pipe will need to be removed to assess the remaining life. Industry standard requires ten percent of the units participate in selective removal of cast iron pipe samples.
In some assessments, the lack of observable failure does not support a global condition conclusion. It is then necessary to send sections of cast iron to a mainland lab for analysis. No lab in Hawaii has the equipment to perform microscopic analysis of cast iron piping. The lab will then report the remaining life of the cast iron tested to the consultant. Your consultant will then use their observations, combined with the lab analysis, to make a recommendation to the owner.