1. Imputed missing values in the following categorical columns with the most frequent value in each of them: 'funder', 'installer', 'subvillage', 'public_meeting', 'scheme_management', 'scheme_name', 'permit'.
2. Imputed 0 values in construction_year with the earliest value of construction year.
3. Imputed longitude and latitude values of records whose longitude were below 29, with the mean values of longitude and latitude when grouped by region_code. The reason was that according to the GPS coordinates of Tanzania (-6.3728253, 34.8924826), longitude values must be over 29. (Refer here)
4. Imputed date_recorded values whose years were before construction_year, with the latest value of date_recorded.

All Imputation values were based on training data. Test data were transformed using those imputation values.

1. Created a new feature called age representing how old a waterpoint is, by subtracting the year of date_recorded from construction_year.
2. Separated out year and month as year_recorded and month_recorded respectively, from date_recorded.
3. Excluded columns id, date_recorded, recorded_by, num_private from training features.
4. Applied Label (Integer) Encoding on categorical features. Encodings were based on training data. Unknown values in test data were labelled as 0 using a custom function.