question: What causes some toilet bowls to have a nearly explosive flush while others are much more “peaceful”?
comment: Depends on the mechanism, but the simpler/traditional methods just have the water fall from the tank to the bowl. Many newer ones (especially meant for commercial) have a pressurized tank, that is the tank is actually a balloon and the water is pushed into the tank at line pressure (usually 40psi or so), when you flush it can then release the water at line pressure (40psi) which forces it though the toilet. Commercial public restroom types (without a tank), skip the tank entirely and just connect the water line straight to the toilet which has the same effect (but requires a very large water line to supply the flow rates).
passages: The double trap siphonic toilet is a less common type that is exceptionally quiet when flushed. There is a device known as an aspirator which uses the flow of water on a flush to suck air from the cavity between the two traps, reducing the air pressure there to create the siphon which sucks water and waste from the toilet bowl. Towards the end of the flush the aspirator ceases being covered in water, thus allowing air into the cavity between traps to break the siphon without the noise while the final flush water fills the pan.
  
  Section::::Bowl design.:Non-siphonic bowls.
   Section::::Design.:Fixtures.
  
  Public toilets by their nature see heavy usage, so they may rely on a flushometer with a stronger and louder flush than a home toilet. Some high-vandalism settings, such as beaches or stadiums, will use metal toilets. Public toilets generally contain several of the following fixtures.
  
  Section::::Design.:Fixtures.:In the lockable cubicle (stall).
  
  BULLET::::- Toilet with toilet seat; whereas a home toilet seat has a lid, a public toilet may or may not
  
  BULLET::::- Toilet paper, often within a lockable dispenser
  
  BULLET::::- Coat hook
  
  BULLET::::- "Pull-down" purse holder
   Section::::Bowl design.
  
  The "bowl" or "pan" of a toilet is the receptacle that receives bodily waste. A toilet bowl is most often made of a ceramic, but can sometimes be made of stainless steel or composite plastics. Toilet bowls are mounted in any one of three basic manners: above-floor mounted (pedestal), wall mounted (cantilever), or in-floor mounted (squat toilet).
   Within the bowl, there are three main waterway design systems: the siphoning trapped system (found primarily in North American residential installations, and in North American light commercial installations), the non-siphoning trapped system (found in most other installations), and the valve-closet system (found in trains, passenger aircraft, buses, and other such installations around the world). Older style toilets called "washout" toilets are now only found in a few locations.
  
  Section::::Bowl design.:Siphonic bowls.
  
  Section::::Bowl design.:Siphonic bowls.:Single trap siphonic toilet.
   Some newer toilets use similar pressure-assist technology along with a bowl and trapway designed to enhance the siphon effect; they use only per flush, or / for dual flush models. This design is also much quieter than other pressure-assist or flushometer toilets.
   Section::::Bowl design.:Non-siphonic bowls.:Washout toilet.
   Section::::Bowl design.:Non-siphonic bowls.:Washdown toilet.
  
  Washdown toilets are the most common form of pedestal and cantilever toilets outside North America. The bowl has a large opening at the top which tapers down to a water trap at the base. It is flushed from the top by water discharged through a flushing rim or jets. The force of the water flowing into the bowl washes the waste through the trap and into the drains.
   Methods used to make up for the inadequacies of low flow toilets include using thinner toilet paper, plungers, and adding extra cups of water to the bowl manually.
  
  Section::::Maintenance and hygiene.
  
  Section::::Maintenance and hygiene.:Clogging.
   Since 1994, there is a significant move towards using less water for flushing toilets. This has resulted in the emergence of low flush toilet designs and local or national standards on water consumption for flushing. As an alternative some people modify an existing high flush toilet to use less water by placing a brick or water bottle into the toilet's water tank. Other modifications are often done on the water system itself (such as by using greywater), or a system that pollutes the water less, for more efficient water use.
   A "true siphonic toilet" can be easily identified by the noise it makes. If it can be heard to suck air down the drain at the end of a flush, then it is a true siphonic toilet. If not, then it is either a double trap siphonic or a non-siphonic toilet.
  
  If water is poured slowly into the bowl it simply flows over the rim of the waterway and pours slowly down the drain—thus the toilet does not flush properly.
   In some countries, clogging has become more frequent due to regulations that require the use of small-tanked low-flush toilets in attempt to conserve water. Sometimes, three to four flushes periodically during the use of a low-flush toilet may be required to prevent clogging, thus using more water than larger-tanked toilets. Designs which increase the velocity of flushed water or improve the travel path can improve low-flow reliability.
   Low-flush toilet
  
  A low-flush toilet (or low-flow toilet or high-efficiency toilet) is a flush toilet that uses significantly less water than a full-flush toilet. Low-flush toilets use or less per flush, as opposed to or more. They came into use in the United States in the 1990s, in response to water conservation concerns. Low-flush toilets include single-flush models and dual-flush toilets, which typically use 1.6 USgpf for the full flush and 1.28 US for a reduced flush.
  
  Section::::Water savings.
   The rapid influx of water into the bowl causes the standing water in the bowl to rise and fill the S-shaped siphon tube mounted in the back of the toilet. This starts the toilet's siphonic action. The siphon action quickly "pulls" nearly all of the water and waste in the bowl and the on-rushing tank water down the drain in about 4–7 seconds —it flushes. When most of the water has drained out of the bowl, the continuous column of water through the siphon is broken when air enters the siphon tube. The toilet then gives its characteristic gurgle as the siphonic action ceases and no more water flows out of the toilet.
   A two-piece attaching seat and toilet bowl lid are typically mounted over the bowl to allow covering the toilet when it is not in use and to provide seating comfort. The seat may be installed at the factory, or the parts may be sold separately and assembled by a plumbing distributor or the installer.
  
  Section::::Water usage.
  
  The amount of water used by conventional flush toilets is usually a significant portion of personal daily water usage: for example, five 10-liter flushes per day use .
  
  Modern low-flush toilet designs allow the use of much less water per flush, per flush.
   Violent crime inside public toilets can be a problem in areas where the rate of such crimes in general is very high. In South Africa for instance, many people have reported being afraid to use public toilets. There have been several highly publicized murders in public toilets, such as the Seocho-dong public toilet murder case in South Korea in 2016. In the US, an infamous case was the murder of a 9-year-old boy in 1998 in a San Diego county public toilet.
  
  Section::::Society and culture.:Anonymous sex.
   After flushing, the flapper valve in the water tank closes or the flush valve shuts; water lines and valves connected to the water supply refill the toilet tank and bowl. Then the toilet is again ready for use.
  
  Section::::Bowl design.:Siphonic bowls.:Double trap siphonic toilet.
   The flushing system provides a large flow of water into the bowl. They normally take the form of either fixed tanks of water or flush valves.
  
  Section::::Flushing systems.:Flush tanks.
  
  Flush tanks or cisterns usually incorporate a mechanism to release water from the tank and an automatic valve to allow the cistern to be refilled automatically.
   During flushing, the user activates the valve via a button or lever, which releases the pressurized water into the bowl at a flow rate much higher than a conventional gravity-flow toilet. An advantage includes lower water consumption than a gravity-flow toilet, or more effectiveness with a similar amount of water. As a result, the toilet doesn't clog easily.
   The lower water level in a dual-flush toilet bowl may be slightly off-putting to visitors to Australia from countries where toilets with a full tank and one lever/button are the norm. However, the lower water level in the bowl was a standard feature of Australian toilets before the introduction of the dual-flush feature, and was not affected by the new type of cistern.
   At the top of the toilet bowl is a rim with many angled drain holes that are fed from the tank, which fill, rinse, and induce swirling in the bowl when it is flushed. Some designs use a large hole in the front of the rim to allow faster filling of the bowl. There may also be a siphon jet hole about one inch (2.5 cm) diameter in the bottom of the toilet.
   If clogging occurs, it is usually the result of an attempt to flush unsuitable items, or too much toilet paper. Clogging can occur spontaneously due to limescale fouling of the drain pipe, or by overloading the stool capacity of the toilet. Stool capacity varies among toilet designs and is based on the size of the drainage pipe, the capacity of the water tank, the velocity of a flush, and the method by which the water attempts to vacate the bowl of its contents. The size and consistency of the stool is a hard-to-predict contributory factor.
   Older installations, known as "high suite combinations", used a high-level cistern (tank), fitted above head height, activated by a pull chain connected to a flush lever on the cistern. When more modern close-coupled cistern and bowl combinations were first introduced, these were first referred to as "low suite combinations". Modern versions have a neater-looking low-level cistern with a lever that the user can reach directly, or a close-coupled cistern that is even lower down and fixed directly to the bowl. In recent decades the close coupled tank/bowl combination has become the most popular residential system, as it has been found by ceramic engineers that improved waterway design is a more effective way to enhance the bowl's flushing action than high tank mounting.
   A toilet need not be connected to a water supply, but may be pour-flushed. This type of flush toilet has no cistern or permanent water supply, but is flushed by pouring in a few litres of water from a container. The flushing can use as little as 2–3 litres. This type of toilet is common in many Asian countries. The toilet can be connected to one or two pits, in which case it is called a "pour flush pit latrine" or a "twin pit pour flush pit latrine". It can also be connected to a septic tank.
  
  Section::::Flushing systems.
   The water may be discharged through a "toilet flapper valve" (not to be confused with a type of check valve), or through a siphon. A float usually commands the refilling device.
  
  Section::::Operation.:Mechanical flush from a high pressure water supply.
  
  Toilets without cisterns are often flushed through a simple flush valve or "Flushometer" connected directly to the water supply. These are designed to rapidly discharge a limited volume of water when the lever or button is pressed then released.
  
  Section::::Operation.:Manual flush (pour flush).
   Until 1 January 2001, the use of siphon-type cisterns was mandatory in the UK to avoid the potential waste of water by millions of leaking toilets with flapper valves, but due to EU harmonisation the regulations have changed. These valves can sometimes be more difficult to operate than a "flapper"-based flush valve because the lever requires more torque than a flapper-flush-valve system. This additional torque is required at the tank lever because a certain amount of water must be moved up into the siphon passageway in order to initiate the siphon action in the tank. Splitting or jamming of the flexible flap covering the perforated disc can cause the cistern to go out of order.
  