Title of the papers:- Profile-Based Control for Central Domestic Hot Water Distribution Authors:- Iglesias, F and Palensky, P Summary:- An average home has 125 feet of 3/4 inch pipe. This holds 3.14 gallons of water. If hot water is used 10 times per day, 31 gallons of water is wasted running the faucets/shower to get the hot water. In a year, this equals 11,461 gallons of water. 25.2 million homes waste approximately 300 billion gallons of water annually.(Premier,15 July 2015) . In another scenario, In a 2009 modeling study, researchers estimated that over 10% of all the hot water drawn for showering in a typical single-family home is wasted waiting for hot water to arrive. If we consider on an average that 200 millions of Americans take shower each day, using EPA estimates of shower water use, that's about 280 million gallons of hot water wasted each day(Osann, 22 Jan 2014) While this can be utilized by simple means such as collecting it and using it for watering and other purposes in most of the cases people are not so concerned to adopt such practices. On the other hand, it becomes still more complicated in the case of showers to follow such measures. A topdown or bottom model can be used to incorporate the engineering aspects in the design prosses using a V-model (Kobak, 2013). The method of analysis: A V-model analysis includes steps viz., Requirement analysis, System design, Architecture design, Module design, Coding, Unit test integration, System test, and final testing and then verification. In this critical analysis, only the design aspects are analyzed keeping the requirements in mind. As the house becomes spacious, pipes need to be made bigger and hence the wait time also increases and thereby the wastage. Even if the flow rates have come down as per the federal standards, there is negligence in reducing the pipes for more efficient fixtures. And as per the survey, it was found that as the housing market rebounds, this increased waiting time reduces the resale value of the homes. Hence along with the water conservation, reducing the water wastage also facilitates to enhance the face value of the house. Two of the leading code-writing bodies – the International Code Council (ICC) and the International Association of Plumbing and Mechanical Officials (IAPMO) have been considering changes for their respective versions of model codes that will be published in 2015.Once brought to the public, these model codes take on the force of law when later adopted by state and local governments.Taken together, the ICC and IAPMO codes are in being followed in almost every part of the world. ((Osann, 2014)) Hence a standard and universal method needs to be formulated to overcome the above problem. The factors which affect the amount of water wasted are: 1. diameter of the pipes.: As the diameter of the water circulation pipes increases the time required for the water to reach destination may reduce but on the other hand, it consumes more energy for heating and there are chances of excess water wastage since more amount of cold water will be stored in the pipes. 2. length of the pipes and spacing: Obviously as the length of the pipes is more the time duration will be more. Hence it is advisable to construct the bathrooms close to one another as feasible. 3. water flow rate: If there is a water-conserving bathroom faucet which delivers half-gallon per minute (GPM) and suppose that piping in the house has 3/4" piping, a 50-foot run from the water heater takes almost three minutes to get hot water to the sink to the bathroom shower and taps. 4. final temperature desired: If the desired temperature is more then, the corresponding time required also will be more. 5. method of heating: the method used for heating also has a significant effect on the heating time. 6. material used. In the prototype, a valve control mechanism is used. When the water has not yet reached the desired temperature the valve will be positioned such that the water will be redirected to a storage tank or toilet flush for reuse. Then when the heating is up to the required temperature the valve directs the water to the required faucet. The electronic mechanism may be devised to control the valve movement and a temperature sensor takes care of the heating threshold. The simplest way of avoiding water wastage is to allow water recirculation. There are 4 basic ways for this 1. Passive Circulation via a 2nd Hot Water Return Line: uses a different hot water line and creates a loop between the water heater and all the plumbing fixtures. This is most economical to install. 2. Pumped Circulation via a 2nd Hot Water Return Line: uses a different pump along with a pipe line. 3. Pumped Circulation via a Crossover Valve: uses a pump and crossover valve between hot and cold water lines. A check valve prevents cold water from backing up and mixing with hot water. 4. Pumped Circulation via a Crossover Valve: here the pump and valve are not connected which allows the pump to be centrally located and the crossover is installed at a further point from the water heater. Earlier and existing related works: The previous and existing methods are: on-demand circulator, wherein a person in the far-off room can use a push button to activate a small pump, which pulls the heated water and sends back the cooled-off water sitting in the pipes to the water heater. A separate piping may be necessary or existing cold water line can be used. Other methods employ structured or home run plumbing system (Wilson, 2009) Many manufacturers have devised HWR systems(hot water circulation) by activating a button at the sink with electrical outlet, but still, it requires an electrician and default wait time. Yet another system incorporates the mechanism in which water continuously circulates through the pipes and hence temperature will always be maintained at desired level. But this happens at the cost of increased enery consumption. Another most protean way is ready for retrofit comfort system. This possesses one-pump and valve combination(Vastyan,2007) it requires only one -valve and one pump combination. Installation time is very less. No return line is required. It includes a timer and is activated when the pump pushes water towards the valve beneath the furthest fixture. Till the water in the hot line is cold, the valve remains open and once it is hot it becomes ready to be sent out. fig1: retrofit comfort system fig2: on demand water circulation fig3(Giannini, 2011): Drawbacks and shortcomings: The performance of the design may vary in the factors on which the waiting time depends, as mentioned above, vary. The electrical part needs perfect calibration and design and hence the system becomes complicated in comparison with the retrofit comfort systems mentioned above. Since the water is redirected to the storage tank, extra piping constructions need to be made. And the tank should be devised to accept the redirected water as well. And self-installation is not feasible. Future work: As mentioned in the journal article (Iglesias and Palensky, 2013), several considerations viz., energy losses and management, user behavioral pattern, control enhancements and simulations of the proposed system may be carried out to make it flawless, end-user friendly and to increase the reliability. Work and research need to be done to make the prototype compact and ease -of-use, in order to compete with simple mechanical systems already in vogue.Whereas the system can be suitably implemented in domestic situations, there is ample scope to upgrade it for industrial application as well. Many leading companies have already brought this water recirculation to practice such as Grundfos, ACT Metlund, Taco, Shower Start LLC.In collaboration with relevant industries, the system can be adjusted to industry standards and brought to end users. The mechanism must be tested for different tank capacities and water flow. The model still needs to be deployed in any practical situation and statistical performance must be recorded. Conclusion: the fact that water wastage is ever increasing even after all the measures undertaken proves that the area needs more and more research and innovations and effective systems to conserve water at the front end. Hence all potential areas must be identified and rectified. It is good to conserve water before it reaches the end-user rather than expecting them to do the job. The model proposed here is a contribution in this regard. The thorough analysis and critical evaluation of the material infer that the methodology is adequate to achieve the proposed goal of water conservation. Though there are some minor flaws and issues, it is very prevalent to the current situation and is a good contribution to the world. The next generations have so much to benefit from the same. Reference:- Iglesias, F and Palensky, P, 2013, 'Profile-Based Control for Central Domestic Hot Water Distribution', IEEE transactions on Industrial Informatics, Volume: 10, Issue:1, pp 697 – 705 Title of the papers:- The Wasteful Wait we Take for Granted ,Tired of Waiting for Hot Water? Authors:- John Vastyan Summary:- The method of analysis: Earlier and existing related works(summary):- Drawbacks and shortcomings:- Future work(summary):- Conclusion:- Reffrence:- Vastyan, J, 2007, tired of waiting for hot water? ,alternergy.com.[ 25 April 2017]  Title of the papers:- Hamwells recirculating shower saves 80 percent of energy, 90 percent of water Authors:- Lloyd Alter Summary:- The method of analysis: Earlier and existing related works(summary):- Drawbacks and shortcomings:- Future work(summary):- Conclusion:- Reffrence:-  Title of the papers:- Domestic Hot Water Recirculation Systems, Water Circulation Pumps & Circulators Authors:- Taco Comfort Summary:- The method of analysis: Earlier and existing related works(summary):- Drawbacks and shortcomings:- Future work(summary):- Conclusion:- Reffrence:-  Title of the papers:- Pipe Temperature Sensors Authors:- http://www.mamacsys.com/pdf/Temperature-Sensor-TE703-704.pdf Plumbing Guide http://www.cairns.qld.gov.au/__data/assets/pdf_file/0014/9014/Recycled_Water_Plumbing_Guide.pdf http://www.citywestwater.com.au/residents/recycled_water.aspx Water Recycling and Reuse: The Environmental Benefits https://www3.epa.gov/region9/water/recycling/