the inventors of the present invention have located a bottleneck in the process for cleaning milking related equipment , and in particular automatic milking systems ams . as is pinpointed by the inventors , in a state of the art washing cycle much time is consumed waiting for the washing apparatus to be filled with water or other washing fluids . today , up to 10 minutes of a total washing duration of 25 minutes is spent waiting for the water to fill up the washing apparatus . the farmer could add animals to the herd and use this waiting time milking the additional animals instead . further , most farms get their water from a local well , whereby the water most often has a low pressure and the time needed to fill the washing apparatus is further yet lengthened . fig1 shows schematically an automatic milking system . an automatic milking system 1 usually comprises one or more automatic milking stations 2 including teat cups , robot arms , a vacuum source , milk meters , a receiver 3 for intermediate storing of milk provided in order to hinder that milk showing a deficient quality is sent further , as well as other milking related equipment . the automatic milking system 1 further comprises a pump 4 for dispatching milk to a milk tank 5 , in which tank milk received during a number of milking occasions and / or from several milking stations 2 is stored . further , pipelines interconnecting the different parts are also included . it is to be understood that such automatic milking system 1 may comprise a larger or smaller number of parts , and that certain parts may be omitted and other , not described parts may be present . the number of parts to be cleaned and included in the washing procedure is not essential for the invention , fig1 only shows exemplary , usually included parts . fig2 shows the washing apparatus for cleaning milking related equipment in accordance with the invention . the milking station 2 and the related parts have to be cleaned several times a day , and a washing apparatus is typically provided to this end . when the milking related equipment is to be cleaned , the milk tank 5 is disconnected and the milking related equipment is connected to the washing apparatus instead . the washing apparatus is further connected to another end of the automatic milking system 1 , usually the teat cups , for enabling a circulation of the washing fluids through the system 1 . in accordance with the invention the washing apparatus is divided into different parts : a separate tank or vessel , hereinafter called a pre - filling tank 7 , and a tank 6 enabling the circulation of washing fluids , hereinafter circulation tank 6 . the circulation tank 6 may in an embodiment simply comprise a reservoir , a temperature sensor and a level guard , and be connected to a pump or the like for enabling pumping the washing fluids through the equipment to be cleaned . the pre - filling tank 7 is connected to the circulation tank 6 , and is preferably placed at a physically higher location than the circulation tank 6 in order to be able to quickly empty its contents into , it , possibly even without the use of a pump . when designing such a washing apparatus , and more particularly when placing the pre - filling tank 7 in relation to the circulation tank 6 , consideration should be taken such that the pre - filling tank 7 is preferably mounted at an easily accessible location enabling an easy mounting and dismounting . this makes it easy to enlarge a system by introducing additional milking stations to be cleaned should the need for such arise . that is , it is simple to connect an additional milking station to an already existing pre - filling tank , such addition possibly requiring the change to a larger pre - filling tank 7 . further , the change from using one pre - filling tank per milking station 2 to using a single pre - filling tank 7 for several milking stations 2 is facilitated . in the pre - filling tank 7 the different washing fluids , usually water and washing chemicals , are prepared . the pre - filling tank 7 may comprise several inlets for this end , for example one for intake of hot water 7 a , one for intake of cold water 7 b and one for intake of washing liquid 7 c . the preparation consists , for example , in heating the water to a desired temperature , if a hot water intake is not provided but only a cold water intake , mixing the appropriate amount of washing chemicals , and also choosing the correct kind of washing chemicals , for example whether it should be of acid or basic type . in accordance with the invention , all these different kinds of preparations can be made in a single tank , not necessitating a multitude of different tanks , thereby providing a most cost - efficient system . in accordance with the invention , the pre - filling tank 7 supplying the water and / or other washing fluids to the circulation tank 6 , is provided with suitable connection means to the circulation tank 6 . only a single pipe , flexible tubing , hose or the like is generally needed as the connection means , the pipe or the like being provided with a suitable valve . the connection means or interface is thus a very simple one , and whether the invention is implemented in a small - sized farm having only one milking station , or if it is implemented in a larger scaled farm having several milking stations but still only one pre - filling tank , the same connection means can still be utilised . further , the present invention may easily be implemented in existing automatic milking stations and existing washing apparatuses requiring only some minor modifications . the existing automatic milking station , and in particular the washing apparatus thereof , should be provided with an intake for connection to an external pre - filling tank , or an existing intake should be adjusted to fit to the innovative pre - filling tank 7 . the costs for such modifications can be regained by the timesavings made , as was mentioned earlier . the circulation tank 6 is usually a part of the automatic milking station 2 . in accordance with the invention the same connection means in an automatic milking station 2 can be utilised irrespective of whether the pre - filling tank 7 is located external to the milking station 2 , that is , shared by several milking stations 2 , or if it is internal to the milking station 2 , i . e . integrated with the milking station ( but external to the circulation tank 6 ) and used only by this milking station . fig3 shows an embodiment of the invention realised in a large - scaled milking farm having n milking stations 2 1 , 2 2 , . . . , 2 n . each milking station 2 1 , 2 2 , . . . , 2 n comprises a circulation tank 6 1 , 6 2 , . . . , 6 n for circulating the washing fluids through each respective milking station 2 1 , 2 2 , . . . , 2 n . in this embodiment a single pre - filling tank 7 can be utilised for several milking stations 2 1 , 2 2 , . . . , 2 n . the preparation of a washing step , for example the mixing of washing chemicals in hot water , can be made centrally . the cleaning can be performed sequentially , i . e . one milking station at a time , or it can be performed simultaneously for all milking stations 2 1 , 2 2 , . . . , 2 n . when the washing procedure is finished , and after each washing step , the washing fluids are led to a drain . the location of a pre - filling tank 7 is preferably determined observing the aspects mentioned above regarding such placement . a single pre - filling tank 7 could be utilised , or two or a few pre - filling tanks 7 could be used , or even a pre - filling tank per milking station , thus providing a very flexible solution . if each milking station is provided with its own pre - filling tank , such tank should be of a more simple , low - cost design . if on the other hand a single pre - filling tank is used for many milking stations , it should be of a more robust kind , including for example supervising means , sensors , alarms etc . the use of a centrally placed , single washing apparatus 6 , 7 to be used by all automatic milking stations within a system is conceivable . washing chemicals can be placed centrally at a single location , preferably in close connection to the pre - filling tank 7 , and away from the milking stations 2 1 , 2 2 , . . . , 2 n . this facilitates the handling of the chemicals , which are often provided in large packages usually weighing some twenty or thirty kilos , in that there is no need to replenish the chemicals at several different locations . such central placement also reduces the risk of any chemical being inadvertently discharged in the vicinity of the milking stations , thereby rendering the handling safer . fig4 shows a method for cleaning a milking station in accordance with the invention . in step 100 a first pre - rinsing step is prepared , while still utilising the milking station ( step 90 ), i . e . while still milking an animal . the pre - filling tank 7 is filled with water of desired temperature , or alternatively filled with cold water that is heated to an appropriate temperature . since this step is performed while still utilising the milking station 6 no time is wasted waiting for the filling of pre - rinsing water . thus the fact that most milking plants have their own wells , which often means a low pressure and corresponding long filling time , has no influence on the cleaning time . the simultaneity of the preparation for the pre - rinsing step 100 and the ongoing use of the milking station is indicated in the figure by a double - headed arrow designated by the letter s , and in the following such double - headed arrows s are used for indicating the simultaneity of different steps . thereafter , in step 110 , the pre - rinsing water is emptied into the circulation tank 6 and subsequently circulated through the automatic milking station and its related milking equipment . while performing this pre - rinsing circulation , the preparation of the main washing step preferably utilising a washing liquid mixed in hot water , is effectuated in step 130 . that is , the pre - filling tank 7 is now filled with a suitable mixture of hot water and a washing liquid . the addition of washing liquid is described more in detail later , and more particularly the determination of the appropriate amount thereof . when the pre - rinsing step is finished the prepared washing water is emptied into the circulation tank , step 140 , after which the washing step is performed in step 150 . while the washing is being effectuated , step 150 , the preparation for an after - flushing stage is made in step 160 . this preparation normally consists in filling the pre - filling tank with cold water , and as soon as the main washing step is finished the flushing water is emptied into the circulation tank 6 , step 170 . thereafter the flushing is performed , step 180 , after which the cleaning method ends . alternatively , any of the steps described can be repeated if need be , i . e . one or more of the washing steps , whereby the same preparations are repeated while the previous step is being effectuated . thus , in accordance with the invention , a subsequent step is prepared before the preceding step is finished , whereby a considerable time saving can be made . the fluid or mixture needed for a step and entering the washing apparatus is thus always ready before a following step in the cleansing process is initiated . this is enabled by the use of a separate pre - filling tank 7 . further , the same pre - filling tank 7 can be utilised for the different steps , thereby reducing equipment related costs and eliminating the need for several tanks . today the washing liquid , or any other chemical to be used , is usually added to the washing water by means of a pump , whereby the measurement of the appropriate amount of washing liquid is performed by determining a pump time corresponding to the determined amount of washing liquid . likewise , the dosing of water is performed by means of pressure control devices , whereby one empty pressure control device is needed for the dosing itself and another one is needed for measuring the water level in the container in question . the use of a pump for dosing the washing liquid has a disadvantage in that the amount of washing liquid added is not reliable over time , and this is compensated for by increasing the prescribed amount of washing liquid over time correspondingly . this entails both a cleanness concern as well as a possible waste of washing liquid . another disadvantage is that the dosing of washing liquids is not accurate . in an embodiment of the invention , the pre - filling tank 7 has an innovative shape , overcoming problems of the state of the art dosing of washing liquids . two examples of such design are shown in fig5 a and 5 b , respectively . the design of the pre - filling tank is aimed at providing a smaller space or section in which the measuring of washing chemicals is made and a larger space or section in which the washing fluid can be stored . in fig5 a and 5 b , respectively , two exemplary designs are shown . the pre - filling tank 7 comprises a body having two sections , a smaller lower section indicated by lv , lv ′ and a larger main section indicated by mv , mv ′, respectively . the cross section area relation between the differently sized sections could for example be 1 to 100 . in the smaller section lv , lv ′ the dosing of liquid chemical is made , for example by using a level indicator , preferably being a sensor of floating type . the dosing of water is performed in the main section mv , mv ′ by using the same level indicator . the level indicator should compensate for the variation of cross section area in a way such that the height always corresponds to a volume with an accuracy of approximately 3 %. by the provision of a smaller lower section an accurate dosing of chemicals is enabled . this innovative design also enables the use of different amounts of chemicals and different volumes of water in different steps of the cleaning process , and from time to time , which is not possible today without manually changing valves and settings before each such change of dosing . the different desired doses of washing fluid and washing chemicals , respectively , can conveniently be pre - programmed by means of the use of a level indicator in the innovative pre - filling tank design . further , in accordance with the invention only a single level indicator , preferably of a floating type , is needed . the above - described dosing system can of course also be used in other applications where chemicals are dosed . further advantages brought about by means of the present invention , and in particular owing to the fact that the pre - filling tank does not constitute an integrated part of the circulation tank , are that the pre - filling tank itself is conveniently cleaned if needed , the pre - filling tank is easily replaceable should such need arise , and the size of the pre - filling tank is easily adaptable in dependence on the size of the automatic milking system and / or other requirements of the automatic milking system .