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3 Different Flushing Actions for Toilets


Approximate dimensions for toilets

Toilets are made in two basic shapes – elongated and round.  According to the expert plumbers in Fort Worth, colors vary (colored fixtures are more expensive than white), but toilets are usually made of vitreous china.  As durable as this material is, it is subject to scratching and chipping and should be handled with care on the job.

There are three different flushing actions commonly used in toilets for residences.  These result from bowl design and, although they have been available for years, few individuals are familiar with their differences or the advantages of one over the other.  Consequently, price has frequently been the determining factor in bowl selection, resulting later in dissatisfaction.

Toilet bowl designs

WASHDOWN:  The washdown bowl discharges into a trapway at the front; it is most easily recognized by a characteristic bulge on the front.  It has a much smaller exposed water surface inside the bowl, with a large flat exposed china surface at the front of the bowl interior.  Since this area is not protected by water, it is subject to fouling, contamination, and staining.  The trapway in the washdown bowl is not round, and its interior is frequently irregular in shape because of the exterior design and the method of manufacture.  Characteristically, the washdown bowl does not flush as well or as quietly as other bowls.

This type of bowl is no longer accepted by many municipal code authorities and many manufacturers have deleted it from their manufacturing schedule.

REVERSE TRAP:  The reverse trap bowl discharges into a trapway at the rear of the bowl.  Most manufactures’ models have a large exposed water surface, thereby reducing fouling and staining of the bowl interior.  The trapway is generally round, providing a more efficient flushing action.

SIPHON JET:  The siphon jet is similar to the reverse trap in that the trapway also discharges to the rear of the bowl.  All models must have a large exposed water surface, leaving less interior china surface exposed to fouling or contamination.  The trapway must be large, and it is engineered to be as round as possible for the most efficient flushing action.

The federal government has established minimum trapway diameters and exposed water surface areas for each of the bowl designs.  The basic differences between the siphon jet and the reverse trap bowls are in these areas, both minimums being larger in the siphon jet to assure better flushing action and less bowl contamination.

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