a huge gas explosion ripped through farmhouse in lincolnshire , tearing down back wall and blowing out windows .
susan house , who lives in the home , miraculously survived because she was out walking her dogs at the time .
her father has owned the property for more than half a century and said it would have to be knocked down .
a bath tub can be seen teetering over the edge of what was once the upstairs bathroom at bleak house farm .